Write A File To As Subfolder Of A InetServer Location

I have an ASP application on IIS server:
http://localhost/myApp
I use ASP and a my own VB activex DLL to create a pdf file and write this
file to a subfolder of the Application folder:
http://localhost/myApp/pdfs

1-
Over IIS I have set the "write permission" for this subfolder.
But each time I receive the message: "Can't open output file (bad filename,
in use by other application)", error 0x80040202

2- a visual basic test application can call this DLL, generate and write the
file without problem to the folder

3- with ASP I generate the file in a normal folder (ie c: emp), it works
Then my ASP page use FileSystemObject to copy this file to the folder
...MyApp/pdfs

When I call this page there is no error message, but the programm runs utils
the line, where FileSystemObject to copy the file to the folder, then it
stops there. The process is hung (dead). The file is not copied...

How can I do?