Hello Erel,
thanks for your reply but, I'm sorry, I forgot to mention that I already tried with IsNull and the error is the same. I splitted the IF statement just to be sure about the error line. Running the program, it stops at line with IF
if IsNull(table1.cell(table1.Colname(k),0)) then
..
else
..
end if
and raises the same error.
Mimmo