Question: Dirac Algebra using the Physics Package

Hi, 

I'm trying to set up the dirac algebra using the Physics package in maple 18. There are dirac gamma matricies (Dgamma) already specified, but I can't seem to manipulate their commutation relations. 

So I've tried building my own: 

restart;
with(Physics);

Setup(noncommutativeprefix = {gamma});

g[1] := gamma[1]; g[2] := gamma[2]; g[3] := gamma[3]; g[4] := gamma[0];

InverseMetric := rhs(g_[`~mu`, `~nu`, matrix])

Algebra :=  (a, b) -> %AntiCommutator(g[a], g[b]) = 2*InverseMetric[a, b];

Rules := Matrix(4, 4, Algebra);

Setup(algebrarules = Rules);

Error, (in Physics:-Setup) unable to set AntiCommutator(gamma[0], gamma[1]) = 0 because, taking into account {AntiCommutator(gamma[0], gamma[0]) = 2}, we would have gamma[0] and gamma[0] anticommutative and AntiCommutator(gamma[0], gamma[0]) <> 0

It seems like Maple can't handle the Dirac Algebra? Or have I done something obviously wrong?

Any help is appreciated. 

Thanks