The top of model shows dark

[Accelerator12]

hello all,i meet a problem,I made a model in blender,and all of things shows fine,but when i turn it to mdx the top of models shows dark(not the dark like shadow)

Spoiler: Model

As you can see,the top shows very weird,there is a way to fix it correctly?very grateful for anyone help me

 

[tillinghast]

i think it was because normals were inverted, try now

 

[yuriy_valandil]

Oh this is cool model can I use it ?=)

 

[Accelerator12]

Oh this is cool model can I use it ?=)

OK,as your wish