Xpages-Problem file upload and download controls

Hi.

I have 3 file upload control and one file download control in a xpage and bind it to a richtext field in a form , added a button with the simple action “Save Document” in xpage.

first I have uploaded 3 files and click the save button.

then I have deleted all the attachments using the delete option in file download control.and I clicked the same save button again.

then i am again uploading all the attachments and click the save button.

I am getting the error “Error while saving the document”…

can u help me with this.