Water Shader - Different depth values between windows and mac.

Update:
Ok, so there were two issues.
1. Very silly bug. When I tested the windows version, the camera was set to player settings, ie. not deferred.
So, naturally, the depthtexture was empty.

2. ScreenPos.Z, which I used to compare depth, needed to be adjusted, like so: Linear01Depth(normScreenPos.z);

Then I could do a comparison between depth screen, and depth water.



I'm working on a water/river shader, and I had it working fine on mac, but on windows the depth buffer looks wrong.
Does anyone know what is causing it, and how to fix? I would like to use surface shaders so that I can easily get proper lighting on the material.

Here are two screenshots showing the difference. Depth is fine on mac, all black on windows.





And here is the depth part of the code:

Code (csharp):

1. void surf (Input IN, inout SurfaceOutput o)
2. {  
3.     float depth = LinearEyeDepth(tex2D(_CameraDepthTexture, IN.screenPos.xy / IN.screenPos.w).r);  
4.     depth = depth/_ProjectionParams.z;
5.     o.Emission = depth;    
6. }

Still working on this water, but currently it looks something like this. I will use the depth value to fade the water towards a depth color, as it gets deeper (as well as increasing distortion amount).