I have just received my HP prime calculator and am trying out some basic functions. In either home or CAS mode, when I try to input an equation to differentiate or integrate, if I press the x,t,theta,n button, it gives me an 'a'. I have the desktop virtual calculator and the ipad app for the prime and inputting the same information it gives me an 'x'.
All three are using the same firmware revision and settings are the same.