Hi,
glActiveTexture is not an exported function of opengl32.dll.
You can use this opengl extension for multi-texturing. You need to get function address of glAtiveTexture using glGetProcAddress. May be Tao framework will handle it.
Possibly your machine do not have ARB_multitexture extension. And therefore glGetProcAddress("glAtiveTexture") will return 0.
glActiveTexture is only supported if the GL version is 1.3 or greater, or if ARB_multitexture is included in the string returned by glGetString when called with the argument GL_EXTENSIONS.
http://www.opengl.org/sdk/docs/man/xhtml/glActiveTexture.xml[
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Please check your machine have ARB_multitexture extension support.
You can use following application to view opengl extensions in your machine.
http://www.realtech-vr.com/glview/download.html[
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