how to lookup cube map texture array in GLSL

[shapeare]

My graphics driver supports OpenGL 4.2

In the fragment program, I use the following code to lookup a cube map array:

#version 420
 
uniform samplerCubeArray cubes;
 
...
 
texture(cubes, vec4(direction, depth));

Then I was reminded to enable the following extension:

#extension GL_ARB_texture_cube_map_array : enable

I compiled and ran, but it still said "unable to find compatible overloaded function 'texCUBEARRAY(samplerCubeArray, vec4)'".
Is the function texCUBEARRAY a funcion of Cg? What should I do?