Parametric Survival Model Fit

["Paul, David A" <paulda@BATTELLE.ORG>]

I am interested in fitting individual Weibull curves to the four subgroups
that
comprise my data.  Here is my code:

        censor.object <-
censor(Time.of.Death,Interval.UpperLimit,Censor.Code)
                WEIB <- censorReg(censor.object ~
strata(Dose),data=Censor.Data)
        summary(WEIB)

When I enter this into Splus (v.6, Win2k), I get the following error
message:

                $"Censor.Data$Dose=0":
                Problem in print: argument right= not matched: print(x[[i]],
prefix = 
                        this[i], quote = ..1, right = ..2) 
                Use traceback() to see the call stack

However, when I change my call above to

        WEIB <- censorReg(censor.object ~ factor(Dose),data=Censor.Data)

there is no error message when I try to obtain a summary of the regression
object.  Is 
this an error in Splus?  Is a summary impossible to obtain when using the
"strata"
argument?  It doesn't appear that the error message has anything to do with
insufficient
data to estimate the model(s).


 David Paul, Ph.D.
  Battelle Memorial Institute
  505 King Avenue
  Columbus, OH  43201
  614.424.3176