[R] error using frailty term

[Mary Slaughter]

Trying to fit a model using the Surv() with a frailty term but get the
following cryptic error message:
------------------------------------------------------------------------------
Error in frailty.brent(sqrt(x), y, lower = 0) :
  Ties for max(y), I surrender
Calls: runplots ... coxpenal.fit -> eval -> eval -> <Anonymous> -> frailty.brent
------------------------------------------------------------------------------
When I remove the frailty term from the model it runs just fine. Does
anyone know what this error message means?

Thanks,
M.