Problem with Background Color for top model in PetraSim Ver 4.2

[mohull 0]

Hello

I am using PetraSim ver 4.2 on Windows 7 and I have problem when I am importing the model.

For no reason it shows the top of model black and when I use View tab to change the background image color it is the same and it does not change.

I have attached the file containing the model and the issue.

Thanks

Mohammad Izadi