I've been trying to implement shadows in my game and I've been following quite a few tutorials online, mainly Riemers, but I'm always getting the same 2 errors when I'm drawing my models and setting the parameters from the effect file. The errors are:

This method does not accept null for this parameter. Parameter name: value

and

Object reference not set to an instance of an object.

So I've then downloaded a sample and just replaced my model with the one found in the sample and the same errors occur. I this find very strange as it works with his model. I'm wondering if the problem is with my models (I made them myself). Here's the code where the errors occur (they start to occur after the second foreach loop).

Any help would be greatly appreciated, thanks.