can't export to excel using win 7 ? (NAV 2009)

hi all... i have developed export data to excel
same server...different client
clients who use win XP can export
but using win 7 ,cannot
how to solve this?
it was said the call to member open failed

is there something wrong with my code?

          TempExcelBuffer.OpenBook(Type + ' ' + DocNo + ' ' +  CompanyInformation."Excel Matrix Name" + ' - ' + RL."No." +  ' '
          + FORMAT(TODAY,0,'<Year4><Month,2><Day,2>') + '.xls','Export');
          TempExcelBuffer.CreateSheet('Export','',COMPANYNAME,USERID);
          TempExcelBuffer.GiveUserControl;