Controlling a text field with a seperate movieclip?!?

Hi I wonder if anyone can help me on this annoying bit of script i am trying to figure out.

I have built a photogallery that loads images and text into an empty movieclip(picture) and textfields(desc_txt, media_txt & credit_txt) from an XML file and displays thumbnails.

I would like to make the text invisble until you RollOver the image. 5 thought thsi would be quite simple but cannot get it to work.

below is the code i am using, with all the textfields placed in a movieclip with an instance of text_mc. can somebody please point me out where i am going wrong or offer any advice, i am so close to the end of this project now its frustrating ther is only this little glitch and one other to fix and i will have done.

Code:
text_mc._alpha = 0;

picture.onRollOver = function() {
picture.onEnterFrame = function() {
if (text_mc._alpha<100 ) {
text_mc._alpha += 15 ;
} else {
text_mc._alpha = 100;
picture.onEnterFrame = null;
}
};
};

picture.onRollOut = function() {
picture.onEnterFrame = function() {
if (text_mc._alpha>100) {
text_mc._alpha -= 15;
} else {
text_mc._alpha = 100;
picture.onEnterFrame = null;
}
};
};