The error you’re seeing is probably caused by v_s's type. If it’s a numpy.array, I think that it is mostly likely of dtype object, and that’s why theano ends up raising a TypeError when you multiply it with beta. If it’s not a numpy.array, then maybe theano does not understand how to make it a shared tensor.
Tensor types sometimes raise errors that are hard to pin down. For example the mentioned in this post was caused because a numpy.array with dtype=object was converted to shared.