Rendering mutiple layers of glass/plastic

[PopaPork]

Hi-  I am trying to render a level that has a couple layers of glass/plastic to it.  Currently if I put a clear glass or transparent plastic on all the parts (vial, and then protective plastic cover) it renders the liquid inside the vial black. 
What settings should I try for the vial, outside protective layer and liquid (which I"m using tinted glass) to get something thats not black?

[m2tts]

In your render settings you need to make sure that your ray bounce passes are set to at least one more than the number of surfaces light needs to pass through. So if you have three layers of transparent plastic and glass that are two sided, then you need to set the ray bounces to 7 (better results if you set it higher of course). If this number is less, then the light will mathematically hit a wall and the result is black.