Problems with formula in google sheet

I have no idea left how to solve the problem:

=WENN(B29="v";SVERWEIS($C$29;Inventarliste!$A$2:$M$109146;3;WENN(B29="m";SVERWEIS($C$29;Merchandise!$A$2:$O$109146;3;))))

I have two when arguments which I need to connect.