I do not execute the same command twice. I want to go this way: f1,p1, f2,p2, f3,p3, f4, p4... Maple correctly solves for f1 and f2, and I get two solutions from display({p1,p2}). However, if I continue to f3, I get an error message.

On the other hand, if I reset everything and start from line 1, execute the next few lines and skip f1,p1,f2,p2 and jump to f3, then I get the right solution at the line f3 and then f4... In summary, I can always get two solutions, either f1 and f2 or f3 and f4, but CAN'T get four of them in the sequence f1, f2, f3, f4.