I have used this API - Parameterization2 Method (ISurface) to get U V min max values for a 2d surface - where spline points like (X -some Value,Y - 0, Z -some Value) lies on that surface. then the API given  Umin = -10000 Umax = 10000& Vmin = -10000 Vmax = 10000.

then I used Evaluate method (ISurface) to evaluate the same surface. the thing is i would like to generate some splines in that surface (by giving UV values as input to evaluate method) but the output from the Evaluate is going away of that surface. why its happening and what to do to evaluate a 2d surface to achieve my requirement like to place splines within the surface ?  Please help me....

thanks in advance.