Two of Oklahoma's 526 school districts received an "F'' under the state's grading system implemented this year, with one getting the grade because it failed to administer enough state-mandated tests, according to a State Department of Education spokeswoman.

Farris Public Schools in Atoka County and Dustin Public Schools in Hughes County were given failing grades in the first report under the system.

Farris Superintendent Wes Watson and Dustin Superintendent Joe Cummings did not respond to phone calls seeking comment.

The Farris district otherwise attained a score that would be a "B," but because the district failed to test at least 90 percent of its students it failed.

Tricia Pemberton, spokeswoman for the State Department of Education, said that failing to test enough students' results is an automatic "F'' on the report cards.

"Farris had a number of testing irregularities with their special education students, and we had to invalidate six scores," Pemberton said.

The prekindergarten through 8th-grade district had 72 students for the 2011-12 school year and six student scores would account for 8 percent, meaning only two or three more students had to not be tested to automatically fail.

The Dustin district received zero points on a 4.0 scale, failing in the following: reading and math performance of all students, which accounts for 33 percent of the district grade; measurement of how those students are improving on state standardized tests, which is 34 percent of the district's grade; and whole school performance, a measure of the district's graduation rate, advanced coursework and student performance on college entrance exams that accounts for the final 33 percent of the grade.

Pemberton said that Dustin's high school and elementary school are not on any of the state's other lists of schools that either need improvement or special attention.