I Am Just Not Getting It....

I've been trying to figure out how to match a particular movie clip to a letter when some enter it?

So, they enter there name: M E G,

for the M (which is displayed) I also want to call or load a movie clip I have of someone signing (American Sign Language) the letter M. So, they enter there name, the timeline jumps to frame 10, where I have a button I want to press that would then search out the matches to the letters and return the appropriate movieclip.

I have tried some various ways, but I'm failing miserably at them it seems.

on (press) {
if (textbox.text.indexOf("M") != -1) {
_root.loadMovieNum(myMovie.swf, 10);
} else {
_root.gotoAndStop("namemissing");
}


I know I'm probably using all this incorrectly-- any ideas???