I think that you may want to examine a few more variables in combination. I think that you can get a message like that when considering the DEPENDENT variable(s) if there is only one value of the random variable associated with a given outcome.
You might try:
proc freq data=datasurvival;
table deceased*Riluzol*center / list ;
run;
And see if a combination of deceased and riluzol only have one value of Center .
From your table I suspect Center=Tours and Riluzol=0 all have the same value for Deceased.
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