Can anyone else think of ANYTHING that could be causing this? If an image loads in under loadimage, shouldn't it also load in under loadtexture?
Are their width and height (i)powers of two and (ii)within the ranges your card can accept? Yes yes, Blitz is supposed to pad out wrongly-sized textures, but that didn't stop it failing to texture a b3d that someone once had problems with because the texture sizes weren't correct. Check your dimensions... at the very least you'll have ruled something else out.