When adopting an adult, it always takes time for them to get used to the routine, what's expected of them, etc. It takes as long as it takes, be patient.
What worked for Engli was that I had a baby gate up, and when she went on the papers, the gate came down and we had some ball time. (it was the dead of winter when she came here) Ball time was her currency, more than food. It got to the point that all I had to do was put the gate up, say 'go pee' and she'd run over and pee on the papers. The gate was only up for a minute. It took time though and we found out what worked for her. Beau got with the program pretty quick too but it was spring when we got him.
Good luck with the new sweetie.
Edit: I just saw that you've had her for 2 years so she's not new. I would be very frustrated too! Well maybe playtime might be her currency too.