Equation in solve app not solving

[Alfon]

Hi,
I put an equation into the Solve app- E1-

L= (P)* (1- (1/(1+R)^N))/R

Then put numerical values into L,P,R and tried to solve for N. I did this by pressing the Num key on the calculator then first pressing Blue-Shift clear to zero out anything in the variables then entering values. Then highlighted the value I wanted to solve for and pressed Solve then nothing happened.
It remained 0 (incorrectly).

Am I missing something here?