I can't seem to get my credit listed on a film I cut in 2009

Have you submitted the credit for consideration?  If so, how long ago?  If it was recent, can you provide the submission ID (you can find it on this page-from "Site Settings" page, "view my contributions"- http://www.imdb.com/updates/history ) from which staff can take a look at the status?

Also, have you supplied any proof/evidence of the credit?  The best would be a screen capture of your name appearing in the on screen credits.

If there is an editor listed who should not be, it could be when submitted, the wrong name was typed in and it should have been yours.  You could submit a request to correct it to your name and explain he's the colorist and credited that way and it should be your name.

To change the name on your page, go to your page and click the "Edit Page" button.  Use the first choice, "Name Correction and Merge" and change "no change" to "Add Correction." Scroll down and click the "Continue" button.  Enter into the name field, "Hart, Matthew C."  Uncheck the box to preserve the "Matthew Hart" or the credits will inaccurately state "as Matthew Hart."  It seems all but one of your credits is currently wrong since, if you've always been credited as Matthew C., those should all have said "as Matthew C. Hart."  But if you uncheck the option, they'll all say "Matthew C. Hart."  If you've been credited differently on any title, you can edit those to say "as..."

I hope that makes sense!  Let us know if that doesn't cover it.