Not able to move or orbit the part

I started following a tutorial. But from the start I have a big, stupid problem. I am not able to move or orbit my piece with the mouse. It’s a .stp part, obtained with Inventor. However I am able to obtain the different points of view: the front, the side, etc. with the software icons.(excuse my anglish I am french)
Thank you!

Some none of those shortcuts works for you ?

View controls in PrePoMax:
• zoom: mouse scroll;
• rotate model: middle mouse button or keyboard arrows;
• pan (move model): Shift + middle mouse button

Ho!! I have a middle button!! I I did not know that! an It work! Thank you very much!
Daniel