Question: Problem about ploting a function...Need help,please~

I'm dealing with a analysis of a mechanical mode with maple12,but I got blocked with ploting a function for a long time.Could you help me with it?Thanks a million!

the expression is below:

arcsin((2.*(22.*RootOf(-73-55*sin(theta[1])+2*_Z^2, label = _L3)+10.*RootOf(-73-55*sin(theta[1])+2*_Z^2, label = _L3)*sin(theta[1])-73.-55.*sin(theta[1])))/(73.+55.*sin(theta[1])));

when ploting that,it appears:Warning, unable to evaluate the function to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct.

however,I can easily got the graph of  "(2.*(22.*RootOf(-73-55*sin(theta[1])+2*_Z^2, label = _L3)+10.*RootOf(-73-55*sin(theta[1])+2*_Z^2, label = _L3)*sin(theta[1])-73.-55.*sin(theta[1])))/(73.+55.*sin(theta[1]))"(we use W to represent it),why maple can't got the graph of arcsin(W)?

Why?what's wrong?How can I get the correct graph?

(the originnal equations set  is {s[3]*cos(theta[3]) = .125*cos(theta[1]), s[3]*sin(theta[3]) = .275+.125*sin(theta[1]), .6*cos(theta[3])+.15*cos(theta[4])-s[E] = 0, .6*sin(theta[3])+.15*sin(theta[4]) = .3;},the variables are [s[3], theta[3], theta[4], s[E]].I need the graphs of s[3], theta[3], theta[4], s[E].what I mentioned above is the result of theta[4].)