I need to ask questions about totals that were calculated from "other deductions". I have been reassessed and they have ignored this amount unless I can verify the amount

There is over $23 K added as other deductions and myself, as well as the CRA does NOT know where this is coming from. I need to verify this deduction as they have disallowed it , until I can explain it. I am not sure if it came from my pension splitting or not...the computer program generated this amount. If it did in fact come from the pension splitting, why is it considered a deduction? Please help.