Question: Quantile and Multivariate PDF

In Igor's "Multivariate Distributions in Maple" http://www.maplesoft.com/applications/view.aspx?sid=6352
he shows how to calculate the Multivariate Normal Distribution. Below I have provided some data
for expected values, covariances etc for a 3 random variable distribution.

Now I try to find the Quantile (with probability 0.05) for such a distribution however Maple fails.
How can I find the Quantile (with probability 0.05) for such a distribution ?


restart:
randomize():
with(Statistics):
with(LinearAlgebra):
with(plots):

N := 3:
X := Vector(N, symbol = x):
EV := `<,>`(.229, -.138, 0.52e-1):
CV := Matrix([[.924, 0.63e-1, -.582], [0.63e-1, .862, -.359], [-.582, -.359, .528]]):
Mpdf := simplify(exp(-(1/2)*(Transpose(X-EV).(1/CV).(X-EV)))/((2*Pi)^((1/2)*N)*sqrt(Determinant(CV))), symbolic);
Quantile(Mpdf, 0.5e-1);


                             /                 2                   
      pdf := 0.3458201174 exp\-4.839130055 x[1]  + 2.236151593 x[1]

         - 5.211318345 x[1] x[2] - 14.21138384 x[1] x[3] - 0.2694161895

                                                                 2
         + 1.037954039 x[2] + 3.269063877 x[3] - 2.212216118 x[2]

                                                   2\
         - 8.752572820 x[2] x[3] - 11.75492333 x[3] /
                                   

                                              FAIL