strange problem with VIZ 4.2

[salf]

Ok, we were doing some renders at work for some bus stop model we're making, sorry i cant post the images but im not at work untill next year.

 

Imagine the regular bus top, this one have a glass roof, an advertising panel on one side an a glass wind break (or glass wall) along the largest side, this glass panel have stickers on it, with the name of the bus route it belongs and a map of the city (those "here you are" maps of the area). Ok, everything is made on autocad except for the "plane" that holds the stickirs, i made a plane on VIZ and assigned to it a material, with a diffuse map and aopacity map of the sticker (jpeg file) i wanted, so you see the glass, with the map on it, and it cast shadows on the floor and such.

 

Ok, so far so good, now heres the problem.

 

Then we decided to add a person to the image, an RPC (i think thats how is it called), so i made another plane on vizz, and add some person diffuse and opacity map material to it, so the person looks ok and casting shadows, but i can no longer see the stickers on the glass panel!!!!

 

So i just moved the position of the persons plane some inches to any side, and the stickers on the glass will appear on the render or maybe not, it was just a randomly thing, but it was linked to the position of the RPC person, why?...no idea, maybe some VIZ error, funnier thing is that, when i didnt see the stickers on the glass panel, even if they werent rendered, they were casting shadows!

 

Even worst, when we made the finally test, on a 800x600 jpeg image, everything looked ok, so we go for the final render, a 3000x2050 .tiff image that takes like 1 hour to render, and it was again without the maps on the glass panel!