Hi Symeoni,

Welcome to the forum.

You only need to put the quotes in correct place, see the revised formula

=IF(AA5="Category Data",VLOOKUP(AA15,'Category Data'!B:G,6,FALSE),IF(AA5="MFR Data",VLOOKUP(AA15,'Unilever Data'!B:G,6,FALSE),""))
If you still have any issues, please upload the sample file. Thanks.

Regards,
DILIPandey


<click on below 'star' if this helps>