2d images with Graphics3d

This appears to work:

Graphics3D 640, 480

;image = LoadImage("mountainst.jpg")
image = CreateImage(300, 200)
SetBuffer ImageBuffer(image)
Line 0, 0, 300, 200
SetBuffer FrontBuffer()

ScaleImage image, 1.5, 1.5

DrawImage image, 20, 20

While Not KeyHit(1)

Wend

Maybe it's defaulting to the backbuffer? Try using a Flip and see what happens.