In the following formula, I cannot get the

=IF(ISEVEN($B20),VLOOKUP($B20,Control,14,FALSE)+VL OOKUP($B20,Control,15,FALSE),IF(AND(ISTEXT($B20),V LOOKUP($B20,Codes,4,FALSE)="Y"),"ENTER",IF(AND(IST EXT($B20),VLOOKUP($B20,Codes,5,FALSE)="Y"),0,"CHEC K")))

My aim is to look at a cell (B20) and do as follows:

If it (the cell) has an even value then lookup that value in another table
and add the two numbers.
If it is text and there is a "Y" in the relveant cell in the lookup, then
display ENTER.
If it is text and there is a "Y" in the other relevant cell in the lookup
then display 0
Otherwise show CHECK.

If I any even number, it works. but if i enter text values, it doesn't.