which Tools version, IP are you using?
Attach few Output images.
few of IP user guides which supports sin function.
Please verify that your application is not working while you think it is not.
As a matter of fact lim(x->0) sin(x)=x, so for small angles the sine of an angle is the angle itself.
Do also note that calculations are in radians, not in degrees and that you are limited to -PI/PI or 0..PI/2 depending on your input parameter.
If you still fail, please provide reply and I will try to make an example (I am just in the middle of project with floating point calculations).
If you would like to use a lookup table, I provided an example where you can generate a .MIF using a .XLS spreadsheet (including VBA macro) and a demo project where the .mif is used to calculate a sine using the lookup table.