如题。

data sasuser.sales111(keep=month cumtotal);
   infile sales;
   input LastName $ 1-7 Month $ 9-11
         Residential 13-21
         Commercial 23-31;
   Total=residential+commercial;
   retain CumTotal 1254657;
   cumtotal+total;
run;
proc print data=sasuser.sales;
run;


log里的内容：

ERROR: No logical assign for filename SALES.
NOTE: The SAS System stopped processing this step because of errors.
WARNING: The data set SASUSER.SALES111 may be incomplete.  When this step was stopped there were 0 observations and 2
         variables.
WARNING: Data set SASUSER.SALES111 was not replaced because this step was stopped.
请各位大侠指教！谢谢！！！