Searching for numbers in one workbook & marking the number in another workbook.

woorkbookA.xlsm

and

woorkbookB.xlsm

The contents/number in column J of woorkbookA has to be checked with column S of woorkbookB.
If the contents/number in column J exists in column S of woorkbookB, I want it to be marked with an X in column U of workbookB.

I've been trying to get this to work, I've gotten some help from others but I'm stuck with this piece of code:

=IF(ISERROR(MATCH(S2;[woorkbookA.xlsm]Blad1!$J$1:$J$13;0));"";"x")

But I keep getting #NAME? errors when putting in the formula in U2.
I've been told it could be regional differences since I use Swedish settings.

I appreciate any help! I'm quite the newbie with excel.

Yay! It does work. However, my next problem:

It did work in my examples, woorkbookA and workbookB.
I want to use this code in the two documents I need to use it in, they're called KAPPREDDD(workbookA) and SEM KUND KAP(workbookB).
I figured that if I change the code:

=IF(ISERROR(MATCH(S2,[woorkbookA.xlsm]Blad1!$J$1:$J$13,0)),"","x")

to:

=IF(ISERROR(MATCH(S2,[KAPPREDD.xlsm]Blad1!$J$1:$J$13,0)),"","x")

It would work the same? But now the cell is filled with a blank space, when it should be marked an X.

Could it have to do with the "Blad1!$J$1:$J$13,0" part of the code? How would I change it to fit my needs?