MapBasic tool not compiling due to undefined variable

Question

I am attempting to compile a quick MapBasic tool I have written, however it won't compile despite the variable being clearly defined

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It's probably something simple I am missing, can somebody point out where I am going wrong?

Answer 1

It was an error later in my code:

I forgot to separate in instance of nMID from the run command string (I didn't have the "&" symbols before it) so it was referring to this instance.

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