For weeks now, The Washington Post has been trying to prove Donald Trump right about something important.

So far, we’ve failed.

The Post has been trying to confirm a claim that Trump and his campaign staff have made repeatedly: that the mogul has given millions of dollars of his own money to charities.

First, The Post looked in public records.

The proof wasn’t there.

Indeed, the tax filings of the Donald J. Trump Foundation — which Trump set up in 1987 to give away his money — show no gifts from Trump himself since 2008. (Filings since then show that all the new money in Trump’s foundation was supplied by other donors. Trump still chooses how to give it away.)

The Post then looked through an internal list compiled by Trump’s campaign, which said the tally showed $102 million in charitable gifts from Trump.

The proof wasn’t there, either.

Reporter David Fahrenthold is investigating how much presidential candidate Donald Trump has given to charity over the past seven years. Here's what he found. (Sarah Parnass/The Washington Post)

The gifts on that list turned out to include “conservation easements” on Trump properties — agreements on land use — and thousands of free rounds of golf, given away by Trump’s courses. Trump’s campaign confirmed that not one dollar of the $102 million was a cash gift from him.

Trump’s staff insisted that those personal gifts existed — but Trump wouldn’t provide any details about them. “There’s no way for you to know or understand what those gifts are or when they are made,” Trump spokeswoman Hope Hicks told BuzzFeed, which has also investigated Trump’s charity.

So The Post looked for evidence of those personal donations, surveying 207 charities (so far) that seemed to have the closest ties to Trump. These were groups to which Trump had given Trump Foundation money, charities he’d written about in his books, charities he’d praised on Twitter — and charities that honored Trump at a charity ball. The firm DonorSearch also provided its database, which includes records of more than 101 million charitable gifts.

All of that turned up just one personal donation — made by Trump, using his own money — during a period of more than seven years.

That was the stretch between 2008, when Trump made his last personal donation to his own foundation, and May of this year — when Trump, under pressure, fulfilled a vow to give $1 million to a veterans’ charity.

The one gift in that stretch went to the Police Athletic League of New York City.

It was worth less than $10,000. It happened in 2009. And there’s a chance it’s actually a bookkeeping error.

As a new week begins, here are the questions we still haven’t been able to answer:

1. Before that $1 million gift to a veterans’ charity in May, when was the last time Trump gave a dollar of his own money to charity?

Trump himself could answer this question but hasn’t. Trump could also release his tax returns, which could detail his charitable giving. He hasn’t. Trump’s staffers have not responded to calls and emails asking for a list of his personal gifts, leaving The Post to build its own list of the mogul’s favorite charities.

On Sunday, Trump’s son, Eric Trump — who runs a charity of his own, the Eric Trump Foundation — denounced The Post’s reporting in an AM radio interview. “Charity is such a big part of our company and of our lives. My father has contributed so much to what I’ve done. He contributes so much to every charity,” Eric Trump said in an interview reported by The Hill newspaper.

But since then, Eric Trump has not provided details to back up those claims.

2. If Donald Trump didn’t donate millions to charity, what became of the $8.5 million-plus he’d promised to give away?

Since 2001, Trump has made repeated promises to give away the proceeds of various ventures: the “Apprentice” TV show; two books; Trump University; and a tent rental to Libyan strongman Moammar Gaddafi. These promises added up to more than $8.5 million in potential donations.

Trump’s lawyers have already said that his personal proceeds from Trump University — estimated by the New York attorney general at $5 million — were eaten up by legal fees. None went to charity. As for the rest of it: If it didn’t go to charity, where did it go?

3. Has Donald Trump ever donated his own money to the Eric Trump Foundation?

The Post included the Eric Trump Foundation on its list of 202 charities, calling and emailing to ask when Donald Trump had last given a personal gift. But the Eric Trump Foundation has not responded to repeated inquiries.

It seems likely that, if Donald Trump gave his own money to any charity, that charity would be his son’s. But so far, neither Donald Trump nor Eric Trump have offered evidence to confirm that. Tax documents, in fact, show money going the other way. In 2014, Eric Trump's charity paid $87,700 to Donald Trump's golf course in Loudoun County, Va., as payment to use the course for an Eric Trump Foundation fundraiser.

4. Did Donald Trump ever give any money to the ALS Association after taking part in its “Ice Bucket Challenge” fundraiser campaign in 2014?

In the midst of the “Ice Bucket Challenge” craze of 2014, Trump filmed a video on the roof of Trump Tower, with Miss Universe and Miss USA dousing him in Trump water. The video now has more than 2.2 million views on YouTube. In one short clip, Trump touted himself, his pageant and his water, while associating himself with a popular charitable cause.

But the point of the Ice Bucket Challenge wasn’t brand-building or YouTube views. It was to raise money for ALS research.

The Donald J. Trump Foundation, however, gave nothing to the ALS Association in the year of Trump’s ice bucket video. Did Trump, perhaps, give a personal gift instead? The ALS Association says it can’t answer that question without Trump’s permission. So far, he hasn’t given it.

5. What happened to this football helmet?

In 2012, at a charity auction in Florida, Trump won a bidding war for gear donated by then-Denver Broncos quarterback Tim Tebow: a jersey and a signed helmet. The winning bid, $12,000, would be paid to the Susan G. Komen organization, a breast cancer charity.

Instead, he used money from the Donald J. Trump Foundation — funds meant for charity and largely donated by other people.

IRS experts have said Trump may have violated rules against “self-dealing,” which are designed to keep a charity’s leaders from using their nonprofit to help themselves. The key question is: What happened to the helmet and jersey? If Trump still has the gear in his possession — perhaps on display at one of his buildings — he may have broken the rules.

If he gave them to another charity, he may be in the clear. But the value of the gear has severely declined, along with Tebow’s football career: Today, a signed helmet and jersey can be bought online for about $415.