fnGetPosition Returns "Cannot read property 'nTr' of undefined" When Called on Table w/ Fixed Cols

I have a table which is split using FixedColumns(oTable,{"iLeftColumns":5,"iLeftWidth":500});

One of the columns on the left side is "editable"; and, after editing the cell I'm trying to use "oTable.fnGetPosition(this)".

The output of "console.log(oTable.fnGetPosition(this))" is "null". If I shift the editable column to the right side of the split, the function returns three values, but the second value starts with zero for the first column to the right of the split (as though the columns to the left of the split aren't there).

The main thing I'm looking for is the first number, the row number of the cell just edited.

Thanks.