Help in basic!

[Lesliect6]

I would like you to help me in dark basic pro, there is something I don't understand and noone could give me an answer on any forums...
So, I want to texture the background of my 3D game, but it doesn't work! The source code is as follows :

backdrop on
load image "filename.jpg", 1
texture backdrop 1

The compiler runs in success, and gives no error messages. But when the game runs, the background is still blue, and it was NOT textured. I have tried in every possible way, but it doesn't work. I even tried putting the whole thing in the main DO-LOOP, but nothing happened. Can you please help me solve this!!
Leslie CT