Actually, when I run your code, I don't see the new object at all.
Run this variation instead:
sync on
sync rate 0
autocam off
box 0,0,256,256, rgb(255,0,0), rgb(0,0,255),rgb(0,255,0),rgb(255,0,0)
get image 1, 0, 0, 256, 256
make object plain 60, 1, 1
make mesh from object 60, 60
make object 61, 60, 2
position object 60, 1.0, 0.0, 10.0
position object 61, -1.0, 0.0, 10.0
point camera 0.0, 0.0, 10.0
texture object 60,1
texture object 61,1
do
if controlkey()
set object cull 61,0
else
set object cull 61,1
endif
fastsync
loop
Use the control key to switch culling on/off.
The problem seems to be that the point order of each triangle is generated wrongly when being converted to a mesh.