i think that that is just what is happening... the shader is using montskysma+6.tga (the statement bmap water_cube=<montskysma+6.tga>;
and then the material is using water_cube as skin1 and the bumpmap texture as skin 2...
don't remove anything from the material code... just comment out the skycube block of code that starts with sky skycube{ ...}
(be right back gotta run to the train station )
--Mike