If you are trying to use the Excel
CONCATENATE function[
^] here, then you can't - that is an "in cell" function, rather than a VB function.
So join strings, use the appropriate VB code directly - that will depend on the version of VB you are using: VB6, VB.NET, or VBA so Google for "concatenate strings" and the VB version and you should find what you need.