Lotus Notes adapter issue

Hi,

IS version: 6.5
LN adapter version: 6.0
Fixes installed for LN adapter:LN_6-0_Fix1 & LN_6-0_Fix2

We have an interface which was working in production till a month ago. But, suddenly it started erroring out:

[ART.117.4002] Adapter Runtime (Adapter Service): Unable to invoke adapter service wm.ln.document.IMPL:save_3.
[ADA.720.514] Lotus Notes Adapter failed to execute method: save(boolean, boolean, boolean) in class: lotus.domino.Document. Reason: Notes error: You are not authorized to perform that operation. Exception ID: 4000

This error is generated at the point when the service, wm.ln.document:save is invoked in the flow.

When I checked with LN responsible team for the access level of the user configured on LN adapter, they said that perticular user has Manager access(read, write, delete).

Any suggestions will be highly appreciated as is it a really urgent issue.

Thanks,
Ashok.