I'm new to opengl es, so this question may be silly but I can't seem to find the answer elsewhere.
I'm developing a feature for one of our iPhone apps that requires the use of opengl es 1.1. The model is dynamically generated based on inputs from the accelerometer. The model generation seems to be working fine with the exception of the shading; no matter what I do the model appears flat (e.g., no shading). I've tried moving the light source to various locations, which changed the overall brightness of the model, but has no effect on the shading the contours of the model.
Here are some details on the model and things I've tried:
1) A png based texture is mapped to the model
2) The model is drawn using triangle strips
3) I've triple checked that the vertex normals are properly calculated
4) I've tried to remove the texture and render with a simple Opengl material and it still appears flat
5) I've explicitly set the shade model to GL_SMOOTH
With my limited OpenGL experience I'm at a loss as to what I should try next. Any help would be GREATLY appreciated.