texture coordinates for multiple texture glsl shader

hello,
i'm workin on a shader that masks and mixes multiple texutres.
i'm fiding a very curious thing;
my 3rd texture (uniform variable tex2 in the code below) doesn't not receive its coordinates properly.
my fragment shader is good old "sh.passthru.xform.vp.glsl" which should pass thru coordinates for upto 8 separate textures.

however, if you look in the code below, line 148, you'll see that i'm forced to use "texcoord1" when i'm reading texture points of "tex2". in this case things work out cuz my textures are the same size and all are in use all the time; however, if i DO actually use "texcoord2" then i only get the color of one pixel, i.e. texcoord2 is constant for whatever reason.

shader and patch are below...

---------------jitter shader xml

    Burn composite operator
    

        texture dimensions
        amp 0
        amp 0
        time 0
        freq 0
    

        amp 0
        time 1
        freq 1
    

        amp 0
        time 1
        freq 1
    

-------------------- patch