In the following command (fln refers to file name)

if fln = " " 
fln = "Temp"
endif

i get this error message

Operator/operand type mismatch

I cannot find the point in my programming at which this variable becomes a numeric reference - but nonetheless Is there a command line i can run immediately before to check if fln is text variable, if not then change it to a text variable before the error message comes up.

thanks
k