Trouble getting Arma 2 Reinforcements retail to work with Steam version of Combined Operations

[fantafuzz (DayZ) 0]

Hello, I am currently having some trouble getting my ARMA: 2 Reinforcements to work with ARMA: 2 Combined operations. I bought reinforcements retail before I bought Reinforcements, and now in DayZ, I can not access the higher resolution textures that come from Reinforcements. I have Reinforcements installed, and I can play it perfectly fine, and I can play Combined Operations and DayZ fine from Steam, but I can not access the Reinforcements additions while I am playing Combined Operations. What can I do to fix this?