How can i close Excel with Microsoft.Office.Interop.Excel dll? AX2009 - Bug?!

Hi,

i need some help with the Microsoft.Office.Interop.Excel dll.

If i execute my code, a excel process were runnig after closing

e.g.:

-----no excel process running---------

--------execute----------

Microsoft.Office.Interop.Excel.ApplicationClass     application;
;

application = new Microsoft.Office.Interop.Excel.ApplicationClass();

application.set_Visible(true);
application.Quit();
application = null;

------excel process is already running-----------

If i execute the same process with another class it works:

-----no excel process running---------

--------execute----------

SysExcelApplication  xlsApplication;

;
xlsApplication = SysExcelApplication::construct();
xlsApplication.visible(true);
xlsApplication.quit();
xlsApplication = null;

-----no excel process running---------

But i need to use the Microsoft.Office.Interop.Excel, because i need a special function which only avaliable in this dll.

I have searched a lot of time to solve this problem, i think it could be an excel or dynamics ax bug?!

Beside I check exactly what MS describe, but i do not get a solution.

http://msdn.microsoft.com/de-de/library/ee317478.aspx

C#:

using Excel = Microsoft.Office.Interop.Excel;
....
Excel.Application excelApp = null;
....
excelApp = new Excel.Application();
.....
excelApp.Quit();
excelApp = null;


Please help me or i despair of this problem. 
Thank you!