Hi @deepakc,
Another user reported that same error here: PKP PN Deposit Error in OJS 3.3 - #3 by jonasraoni
The recommendation was to upgrade OJS 3.3 to a later version to help remedy the issue. I would recommend trying that, as OJS 3.3.0-13 and the PKP PN plugin will have been updated since then. If the error still persists after the upgrade, please report back.
-Roger
PKP Team