主题：如何才能读出正确的持仓量？

             bb  := STKLABEL;     
                            if    STRCMP(STRLEFT(bb ,2 ), 'AU')=0    then  begin
                             nn ：=  'AU' ;                              //沪金
                     end
                        
                            if   STRCMP(STRLEFT(bb ,2 ), 'AG')=0    then   begin          
                             nn ：=  'AG' ;                               //沪银
                    end                 
                           
                           a:=  "STRCAT(nn ,'01$openint')" ,noaxis ;      // 读取01合约的持仓量
                           b:=  "STRCAT(nn ,'02$openint')" ,noaxis ;      // 读取02合约的持仓量  

          问题：读不出持仓量，分析问题出在a、b的定义上，如何才能读出正确的持仓量？