Hi:
  
PROC REPORT is not like a DATA step program. The variable you want to show or use in the COMPUTE before block may not be available to PROC REPORT. Remember that PROC REPORT has a couple of rules that control behavior:
                
1) Left to Right rule:  PROC REPORT builds each report row from left to right, as variables are listed on the COLUMN statement. So, for example, in the COLUMN statement below:
  COLUMN REGION SUBSIDIARY PRODUCT SALES RETURNS;
There is no visibility of SUBSIDIARY or PRODUCT inside the COMPUTE block for REGION. 
                        
2) Every variable you use in a PROC REPORT step MUST be in the COLUMN statement or must be a temporary variable. So, for example, if you had this COLUMN statement:
   COLUMN REGION PRODUCT SALES RETURNS;
 
Even if SUBSIDIARY was in the input dataset, if it is not even listed in the COLUMN statement, it will not be available to you for testing or using in a LINE statement.
                       
I do not know which of these situations you are encountering, but I suspect that one of these rules is what is causing the blanks to appear. Refer to this paper for some ideas of how to accomplish different break processing. 
 
http://support.sas.com/rnd/papers/sgf07/sgf2007-report.pdf
            
cynthia