Don't use square brackets in Prime unless you really know what you do!!
Typing square brackets create a matrix which, as I think, was not intended here.
Replace them by 'normal' parenthesis and your approach will work OK
Personally I prefer using the "CreateMesh" function because is gives me better control over axis limits and mesh size.
The setting options for Prime's 3D plots are quite pathetic and the formatting options are nowhere near what you should be able to expect from such a programme nowadays. Also note that the axes do not intersect at the origin and there is no way to force this. There is also no way to scale the axes equally - you would have to manually set the limits on all axes at the same distance and doing this is quite tedious in Prime.
BTW, why do you call it a "complex function"?
Its just a real-valued, simple quadric.
