I am receiving a type mismatch error on the below code.

Range("SUB!D" & i).Value = Range("SUB.CSV!D" & x) + Str(Range("SUB.CSV!F" &
x)) + " /" + Range("SUB.CSV!E" & x)

The problem is the Range("SUB.CSV!D" & x) piece of the code can sometimes
have characters, sometimes it has numbers, it varies. Is there a way around
this?

Thank you