PHILADELPHIA (AP) — An appeals court says a U.S. judge erred in calculating the 25-year sentence of a former Ivy League professor convicted of child pornography.

Lawrence Scott Ward [pictured] was convicted of manufacturing child pornography and lying to authorities to get a Brazilian teen victim into the U.S.

The 67-year-old Ward formerly taught at the University of Pennsylvania’s Wharton School of Business.

The 3rd U.S. Circuit Court of Appeals on Wednesday ordered U.S. District Judge Petrese Tucker to explain how much time she was ordering for each count.

Federal prosecutors say the 67-year-old Ward preyed on vulnerable teenage boys as he pursued them for sexual encounters and pornographic videos.