Several hundred carpenters, electricians and plumbers at the National Agricultural Center in Beltsville got some good news and some not so good news yesterday when they opened their pay envelopes.

The good part was that they finally got the retroactive portion of the 3 1/2 percent federal pay raise that went in effect in January, about $25 a person.

The bad news was that was all they got. Their regular paychecks -- representing two weeks of take-home pay ranging from $200 to $500 -- were not in the envelopes sent up from the finance center in New Orleans.

Nobody is quite sure what happened.

Departmental officials yesterday pushed for another press run on the checks and hope to have them delivered to Washington today. If that doesn't work they are looking into other ways to get full or partial payments to employes who have rent and bills to pay, and financial needs over the weekend.

"We don't know exactly what happened, but we are going to find out," an official said yesterday. "We are fully aware of the employes' problems, and we are going to do everything possible to get their money to them as soon as possible."