ISNA not working as expected

I am trying to use an IF(ISNA formula to eliminate any #N/A entries from occurring in my sheet, but when I ctrl shift enter (array formula) none of the #N/As go away. The formula still works for the cells that return values, but it doesn't eliminate the #N/As. Any ideas? Here's the formula:

=IF(ISNA(OFFSET(Table,0,MATCH("Commissioning Completion",OFFSET(Table,0,0,1,COLUMNS(Table)),0)-1,ROWS(Table),1)),"",(OFFSET(Table,0,MATCH("Commissioning Completion",OFFSET(Table,0,0,1,COLUMNS(Table)),0)-1,ROWS(Table),1)))

It seems to work for me on a sample I tried to reverse-engineer from your formula...

But perhaps putting up your actual spreadsheet sample (or facsimile) would help.