something strange is happening, $replace not working

[RhoSigma]

As you don't show us the actual replace function, I can only make the best guess, that you misspelled the function name in the call in line 9. Hence, the compiler doesn't recognize Replace$ as a function and going to think its an un-DIMed array. But as you give strings in the paranthesis, where an array would expect index numbers, you get the "illegal string-number conversion" error.

It's one of those errors, where the error doesn't really has a connection to the real mistake, but is just caused by a "symtom" of it.

Check the function name, that's most probably the cause of it. (StrReplace$() maybe??)