1) That's a solve BLOCK. Please read and write more carefully.
2) What version are you using?
3) What are you putting in the Solve Block and how are you constructing the block? Did you use the numeric solve or the symbolic solve?
I couldn't get v14 to have any of the troubles you describe. My first suspicion is the user's familiarity with MathCad. Let's see what you are trying that doesn't work.