choose Excel Com Server Version

I try to choose which excel version should create the output i have installed both 2003 and 2007 i check with regedit # HKEY_CLASSES_ROOT\Excel.Application # HKEY_CLASSES_ROOT\Excel.Application.11 # HKEY_CLASSES_ROOT\Excel.Application.12

switch typ 
            case 1 
                [file,path] = uiputfile('*.xls','Save selected data'); 
                Excel = actxserver('Excel.Application.11'); 
            case 2 
                [file,path] = uiputfile('*.xlsx','Save selected data'); 
                Excel = actxserver('Excel.Application.12'); 
            otherwise 
                return; 
        end     fileName=fullfile(path,file); 
      if ~exist(fileName,'file') 
           ExcelWorkbook = Excel.workbooks.Add; 
           ExcelWorkbook.SaveAs(fileName) 
           ExcelWorkbook.Close(false); 
      end 
      ExcelWorkbook = Excel.workbooks.Open(fileName);

for case 1 it works fine case 2 not

??? Invoke Error, Dispatch Exception: Source: Microsoft Office Excel Description: Die Open-Methode des Workbooks-Objektes konnte nicht ausgeführt werden. Help File: C:\Programme\Microsoft Office\OFFICE11\1031\xlmain11.chm Help Context ID: 0

Error in ==> dataSave at 25 ExcelWorkbook = Excel.workbooks.Open(fileName);

Error in ==> Velo2Xls>save_Callback at 321 dataSave(handles.time, handles.outdata, outHeader);

??? Error while evaluating uicontrol Callback

any ideas?