iColumn is declared as an integer, but the formula will not return an integer.
I think you are looking for a specific column in the header row. If you are then use the FInd method which will return a cell and from that get the column number.
Also, put the code into the UserForm not a Module.
I'm not very knowledgeable in VBA. would be greatly appreciated If you can help me fix it in a submission that I don't know. thank you very much