D.C. school report cards that were supposed to be distributed at parent-teacher conferences Wednesday were not available at two high schools and were late at an unknown number of other schools because of a variety of errors, school officials said.

Report cards for Wilson High School's 1,500 students were not printed at school system headquarters until yesterday morning and then were found to be replete with errors, Principal Stephen Tarason said. The report cards will be corrected over the next few days and mailed to students' homes, officials said.

At 489-student Duke Ellington High School of the Arts, no report cards were printed because the school never picked up the grading sheets that teachers are supposed to fill out, Assistant Superintendent Ralph Neal said. A data entry clerk in each school's office is supposed to scan the grades submitted by teachers into a computer, which transmits them to headquarters.

"The work was not done," said Neal, who oversees the senior high school division. He could not say why the sheets had not been picked up.

Report cards for the first term of the school year, which ended Nov. 5, were supposed to be available at parent-teacher conferences, which were held from noon to 7 p.m. Wednesday.

But officials at school headquarters did not finish printing report cards for several high schools until about 2 p.m., meaning that many parents who arrived for conferences earlier in the day left without seeing them.

School system spokeswoman Denise Tann said report cards for some Ballou High School students and for seventh-graders at Winston Educational Center were not ready at all on Wednesday. They will also be mailed home.

Neal said one problem was that a new labor contract gave teachers more time this year to submit their grades, leaving only 48 hours from that deadline to the time report cards were supposed to be available to parents.

At Wilson High, the machine that scans the grading sheets was not working, so they were brought to headquarters Tuesday to be scanned into the computer, Tarason said. A school official called headquarters Wednesday and was told the report cards would be ready at 2 p.m., then at 6 p.m., then Thursday morning.

The reasons for the errors were unclear. Tarason said the grading sheets may have been printed slightly off-center, so that the computer misread the grades the teachers filled out.

One Wilson teacher said the cards were wildly inaccurate, with some students receiving F's instead of A's, and others showing many more absences than they had.

Neal said he had not been told of similar problems at other schools.