Hundreds of tests taken by high school students last May for college credit are missing sections, says the Educational Testing Service of New Jersey.

The advanced placement tests are taken by students in the United States and abroad who hope to get a head start on their college education.

ETS spokesman Tom Ewing said they found some of the tests lack the essay section while others do not have the score sheet for the multiple-choice portion, the Washington Post reports. He said the number of exams affected is in the hundreds, not the thousands.

One high school in Israel has been told that 54 different parts of 81 exams have been lost while the Edmonton Journal reports essays for 168 students who took the test in Canada are missing.

Ewing said each year some score sheets go missing either at the schools where the tests are taken or during the shipping and unpacking process.

During the months of May and June, ETS receives 2.3 million boxes of the tests.