how to solve Texture is not accessible error and Can't read from cubemap error?

I am gitting Texture is not accessible error and Can't read from cube map error when I try to load my asset bundle. My asset bundle contains a sphere with a Skybox/Cubemap material and a cube map texture in it. My sphere is getting loaded but the cube map texture is missing. and getting the above error.

I have tried browsing my asset bundle using Unity Asset Bundle Browser. I can see all three of them. where is it going wrong please suggest me?