IF/THEN in PROC SQL statement of SAS

Having problems with an IF/THEN statement in a PROC SQL; statement of SAS.  What am I missing or doing wrong?  Not even getting any errors...just not doing what it should:

proc sql;
      create table NEW_TBL as
            select distinct
                  FIELD1, FIELD2, FIELD3, FIELD4, FIELD5,  
                  %IF &lob. = 'monkey' %THEN
                  %DO;
                        FIELD100,
                  %END;
                                                FIELD6, FIELD7
            
      from OLD_TBL;
      quit;