title: Error in Proc Freq
body: <p>I am have a data set with multiple visits with 2 treatment arms and a Vehicle group. Also i have a variable say "SSA" having two values 1 and 0. here 1 stands for responder and 0 for non-responder subjects. while performing Proc Freq for chi-square statistics i am getting the following error. Here is the code i used</p>
  
  <pre><code> PROC FREQ DATA=P&amp;V1;
         TABLE TREATMENT*SSA/CHISQ ;
         WHERE TREATMENT IN (1 &amp;TR1); *(&amp;tri for treatment 2 and treatment 3);
   RUN;
  </code></pre>
  
  <p>NOTE: No statistics are computed for TREATMENT * SSA since SSA has less than 2 no missing levels.
  WARNING: No OUTPUT data set is produced because no statistics can be computed for this table, which has a row or column variable with less than 2 no missing levels.
  this error is for my last visit where i am having a single value 0 in all treatment groups and Vehicle.</p>