I tested your code by changing the models to a cube and sphere, and they showed. There are a number of problems that could be the cause of your models not showing...
1)Did you use the right path?
2)Did you include the image in the SAME file as the model, this is an important one.
3)Could be that the models are either too large or too small, so if the above 2 don't show results, place this in the loop,
set cursor 1,1
print "object size x(1) = ";object size x(2)
print "object size y(1) = ";object size y(2)
print "object size z(1) = ";object size z(2)
print "object size x(2) = ";object size x(3)
print "object size y(2) = ";object size y(3)
print "object size z(2) = ";object size z(3)
This should let you know the size of the object, and if its too big, then size it down,or if its too small.
4) You could also try to turn off autocam, this will point the reposition the camera, so if the object exist, you WILL see it.