ods output homtests=p(where=(test='Log-Rank'));
  proc lifetest data=ana;
  time aval*CNSR(0);
  strata trtpn;
run;

NOTE: The LOGLOG transform is used to compute the confidence limits for the quartiles of the survivor distribution. To suppress
      using this transform, specify CONFTYPE=LINEAR in the PROC LIFETEST statement.
WARNING: The likelihood ratio test for strata homogeneity is questionable since some strata have no events.
NOTE: The data set WORK.P2 has 1 observations and 4 variables.
NOTE: Compressing data set WORK.P2 increased size by 100.00 percent.
      Compressed is 2 pages; un-compressed would require 1 pages.
NOTE: PROCEDURE LIFETEST used (Total process time):
      real time           0.06 seconds
      cpu time            0.04 seconds

值是求的出来 但是就是有这个warning 不知道该如何去除。。。求大神帮忙。