Unable to extrude the selected...

Hello, 

I'm new here , so I bought yesterday the licence for CorelCad 2018 . 

Im trying to draw an 3d object.

I tried the simplyest way i draw a rectangle and then i wanted to extrude it but i receve every time this measge : Unable to extrude the selected...

I aslo tried to draw an solid Box but after i started i couldent see anithing on my display. Could be something from settings?