Thread: Classpad "Incorrect Argument"

Can anyone help with this please? I am trying to find derivatives and indefinite integrals on my Casio Classpad. I am entering it correctly, but it now keeps telling me "Incorrect Argument". I have done heaps of these before with no problems. It is in Alg mode. When I put it in Assist mode, it works. Shouldn't it be the other way around???? Today I downloaded the new OS. Could this be the problem?

I have the exact same problem as this member here and I see no replies to this topic. How do I fix this problem?