Prince of Persia

Hi, when I edit level 5 in the editor, and select the usual background bricks, everything looks normal. But in the game, they have changed to the blue sky. Does anyone know why this is?
For the level I just had to swap the plain bricks for the one with the stripe running through (middle level in the picture), and everything is ok. No big deal, just curious.

This might be related to the background animation.
(There was one case when that was causing a background to be drawn differently: viewtopic.php?p=11982#p11982 )
Click one of the tiles that produce the error and look at the number in the box between the graphics dropdown lists.
If it's not zero then change it to zero.
If it's zero but you still encounter this -- please tell me.