Question: Some warnings when using ResponsePlot command,puzzling...

Hi,

I use maple to verify some examples in my textbook. The followings are two warnings which I came across.

1.

> with(DynamicSystems); sys := TransferFunction((1+.2*s)/(1+.1*s));
> ResponsePlot(sys, Step());

When running the codes above, a warning appears unexpectly.
Warning, cannot evaluate the solution past the initial point, problem may be complex, initially singular or improperly set up

With this question, I try to use inverse laplace to plot the step response:

> f := proc (x) options operator, arrow; (1+.2*x)/(x*(1+.1*x)) end proc;
> with(inttrans);
> g := proc (t) options operator, arrow; invlaplace(f(s), s, t) end proc;
> plot(g(t), t = 0 .. 1.5, y = 0 .. 2);

After running the codes above, the curve appears.

Why the ResponsePlot command don't work? And how to conquer this warning when using ResponsePlot? Can you tell me some details?

2.

I substitute Step() for Sine(), and make the duration=40, then another warning appears.

> ResponsePlot(sys, Sine(), duration = 40);
Warning, cannot evaluate the solution further right of 22.937821, maxfun limit exceeded (see ?dsolve,maxfun for details)

I feel bewildered about the content of the help page when clicking the hyperlink. Can you tell me how to conquer this warning?

Thank you very much!