When i download the .dm file from the server. It installs the sis file successfuly on my handset 6630; but it gives the error "Unable to read file "

I used the following method to create the .dm file

1. I created a .def file in the textpad and just wrote "application" in it.(Without quotes). So i have a MyApp.def file which contains the string "application"
2. Now i package MyApp.sis and MyApp.def in a zip file and rename it to MyApp.pip
3. I now open NMIT 4.1 and then make a .dm file (just using forward lock option) . I load the MyApp.pip file there and specify the content-type as application/x-pip
4. I save the file as MyApp.dm

5. Now i upload it to my web server and add the following MIME types on the server
AddType application/vnd.oma.drm.message .dm
AddType application/vnd.oma.drm.content .dcf
AddType application/vnd.oma.drm.rights+wbxml .drc
AddType application/vnd.oma.drm.rights+xml .dr

Now when i download this MyApp.dm file OTA; it installes succcessfully but gives a message "Unable to read file".

When everything is working successfully why this error is coming;i dont understand.

If anybody encountered similar issue ...please let me know how to solve it.