here is what happened to me last year.
My federal last name is different than my state last name (long story, not worth talking about here). anyways when i first signed up for the DAT i used my federal last name, but then decided that since all my certificates, transcripts, and college degree had my state last name that i would change it. I called ADA, asked them to change it and they said they changed it. And when I went to the DAT center, I didn't ahve any problems taking the test and getting my score with the "new" name. However, where I got problems is when ADA sent my scores to the schools, they sent it under my federal name, and thus not lining up with my application file. I had to contact each school to tell them where my DAT scores where. Lots of pain, espically since every school kept telling me that they don't have my scores until I figured out they actually do but not in my file!
so call them once, then call them again, and after you take the test call them again to make sure it got changed correctly