[OpenGL3.2]Error in glTexSubImage2D with GL_TEXTURE_CUBE_MAP as target and height and width are not same

[OpenGL3.2]Error in glTexSubImage2D with GL_TEXTURE_CUBE_MAP as target and
height and width are not same

I am using glTexSubImage2D with GL_TEXTURE_CUBE_MAP as target. It is
giving me GL_INVALID_VALUE on my driver if height and width are not same .
I am not sure of this type of driver behavior.As far as i know, it is not
mentioned in glTexSubImage2D man page on Khronos.org. Does anyone faced
this?