Unable to save as excel file problem

I have one website run/call vb6 application. When running the website in local the excel fill will be created and save it in somewhere (all this done by the application, the vb6 source code is working well). But when i upload the website into server. The server cannot save the excel but the server has excel 2007 and able to create the excel file but only cannot save it,normally it only take less than 5 seconds. to save the excel file (in local test).... Why? Below is my code for save the excel file (in the application).
 
oBook.SaveAs (App.Path & "text.xls")