Why is GLEE failing with glClearIuiEXT()? [migrated]

I'm trying to test using GLEE for the first time. I seem to be following the book fine. However, this condition passes, but the function does not set the clear value. At least, I get a black screen. glClearColor works, however.

if (GLEE_VERSION_2_0 && GLEE_EXT_texture_integer)
    glClearColorIuiEXT(128,128,128,255);

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);