Mesh Texture Issue

[Carbon Philter]

Hi all. Need some advice on problem being experienced,please.

I've constructed a mesh hull and am test texturing it on the Beta grid. On one side the texture is applied correctly and I've used the Bumpiness setting on Brightness to give some additional depth.

 

The other side of the hullaccepts the texture no problem, but when I apply the Bumpiness setting I lose all the colour as following pics show.

 

 

 

However, if I use Darkness rather tha Brightness, it displays the colour.

 

Can anyone advise - is this standard behaviour because it's all one mesh even though it's different texture faces?

Alternatively, could it be down to my graphics card? - never had any probs in the past and get decent performance despite having one of the dreaded AMD cards. Or could it maybe even be down to being on the beta grid?

I know I can just use the basic image on both sides without the bumpiness setting but it just gives that added depth to the texture if I could use it.

Any advice welcomed.

Thanks

Carbon