Different scope result for two different run times

Here are two scopes of the same simulation run for different run times 50s and 100s. For 50 s, the concerned parameter remains constant but not in case of 100s, it starts changing after ~17 s, but in negligible magnitude. has anyone faced the same problem, if yes, is there any explanation to it.

here are the images: 50 s: http://i.imgur.com/CKVlm9M.png

100s: http://i.imgur.com/G7EamI8.png

[Kiran Sagar]

i have not disturbed/changed the scale of the graph.....in case somebody thinks that way

Answer 1

[Azzi Abdelmalek]

I 've faced the same problem, I was using 1/p block. But could not find the explanation.

[Azzi Abdelmalek]

The only logical explanation I can guess, is: if the solver's step time is set to variable, then for different stop time, the variable step time changes differently.

[Kiran Sagar]

seems a bit long shot but its the only possible explanation.......yes the solver is set to variable......any possible solutions ????