How to pass variables to attachMovie syntax

I’m trying to create a function that can pass a variable to an attachMovie syntax. I’m doing this incorrectly, and I’m having difficulty looking for the right language to find out how to solve this problem. The movieclip that I am attaching is being exported with a “-m”, and so I thought I would use the syntax ‘variable + “-m”’, which is not working.

If anyone can point me to the right resource or has a simple answer for this, that would be great:

go (passThis);

function go (passer) {
_root.attachMovie(passer+"-m", passer, 1);
}

Thanks.