multitex fragment shader issue for different sized textures

[pitbool]

Hi,

I am trying to blend an algae texture to a sea floor texture. The algae texture file is a 512x512 jpg image. I am retrieving the other texture from our ocean osgb model. This texture is a 1024x1024 baked into the model.

I have tried four ways (see below), but unfortunately, none works!
All are shaders, except for the first.

1. Using texblend - this gives some kind of blending, but it is non-uniform and not upto our expectations.
2. Using the texBlendFP.frag shader - the first texture do not show up at all.
3. Using the custom blend shader from \examples\shader\tutorial_multiTexture.py - the first texture do not show up at all.
4. Using the code from multiTexture.py (Tutorial: Multi-texturing) - strangely, same result as in option 1 above!

I have attached the py file in txt format here.
Any suggestions on how to get this to work?

Thank you!