glLineWidth not work on OpenGL ES 1.x Vincent

Hello everybody,
I’m using the OpenGL ES 1.x Vincent in a software I’m developing and I am not able to change the width of the line with the function glLineWidth. I develop in Windows environment (Visual Studio 2005) for devices with Windows Mobile / CE. Does anyone have any idea what might be happening? I’m already thinking that this function is not implemented in this library.