R help - Mar 2006 - MCMCpack Ordinal Probit Help

Hi everyone,
I am running an ordinal probit using the Bayesian MCMCpack and I am getting an
error saying "attempt for find suitable starting values failed"

Here is my code:
>  posterior <- MCMCoprobit(y ~ x1 + x2 + x3 + x4 + x5 + x6 + x7 + x8 +x9
+ x10
+ x11 + x12 +x13 , beta.start=c(-10, 0.05, 0.02, 0.04, 0.98, 0.61, -0.29, 0.91,
-0.82, 1.34, 0.68, 0.57, 0.09, 0.5), mcmc=10000)

Here is the error:

Error in polr(ordered(Y) ~ new.X) : attempt for find suitable starting values
failed

I don't understand why it cannot find suitable starting values if I have
specified those in beta.start().

Thanks a lot,
Nadya Toskova
PhD Student in Marketing