That's a very strange problem. It works fine on my 8320. I tried holding the SHIFT key and I was able to type in caps while I held it down, I tried just pressing the SHIFT key once then letting it up and the next letter I typed was in caps.
I guess I don't understand the issue much from the way you described it. You're trying to type two letters at the same time or just trying to hold the SHIFT key down while pressing the letter you want to capitalize? If it's the latter, just press and release the SHIFT key. That's all you need to do really.
Dave