Without being able to see what the variables are set as i would think that your starting point would be to set a stop at this row and hover your mouse over the variables to see what they are at this point - irow, icolumn & extab

"exTab.Range(Cells(1, 1), Cells(iRow, iColumn)).Select"

Its possible that there is nothing in the used range when assigning the variable here or the workbook references isnt open

iRow = exTab.Worksheets(1).UsedRange.SpecialCells(xlCellT ypeLastCell).Row
iColumn = exTab.Worksheets(1).UsedRange.SpecialCells(xlCellT ypeLastCell).Column

If you know to do it you can set watches on these variables as well as the stop which makes it easier to debug.