How to respond to question when using sum function

Hello,

 

I am a new user of maxima and have run into a difficulty. I wanted to sum
the geometric series (because I know what the answer is and could use this
to check that I'm using the function properly).  These are the steps that I
took:

 

1.       From the toolbar, I first chose 'Calculus' and then selected
'Calculate sum'

2.       A 'Sum' dialogue box appeared. I entered p^(k-1) into the
'expression' box, k in the 'variable' box, 1 in the 'from' box, and 5 in the
'to' box. I then put a check in the 'simplify' box and clicked OK.

3.       A prompt then appeared on the screen: 'Is  abs(p)-1  positive,
negative, or zero?'. 

4.       How do  I enter a response? When I type a response after the prompt
(ie negative), nothing happens. I can't find anything in the documentation
about how to respond to the question.

 

Any help would be appreciated.

Ellen