  We give an interpretation of Yetter's Invariant of manifolds $M$ in terms of
the homotopy type of the function space $TOP(M,B(G))$, where $G$ is a crossed
module and $B(G)$ is its classifying space. From this formulation, there
follows that Yetter's invariant depends only on the homotopy type of $M$, and
the weak homotopy type of the crossed module $G$. We use this interpretation to
define a twisting of Yetter's Invariant by cohomology classes of crossed
modules, defined as cohomology classes of their classifying spaces, in the form
of a state sum invariant. In particular, we obtain an extension of the
Dijkgraaf-Witten Invariant of manifolds to categorical groups. The
straightforward extension to crossed complexes is also considered.
