Make sure her number is under Mobile 1. I had a contact with two cell numbers in my voyager. Mobile 1 and Mobile 2. Then she got rid of Mobile 1 number, so I just deleted it.
When I transferred all my contacts, it was a real pain to txt her, because it wouldn't give me the option to text her. I figured out that DROID doesn't have a MOBILE 2 spot, and it put her number in NOTES.