Hi @mellat,
For problems such as these, it is necessary to check the PHP error log, to be able to troubleshoot the error. Oftentimes, the person responsible for running the journal will have to do this (or a systems administrator) - I wasn’t clear from your question whether or not this is you. If this is not you, you can encourage the person running the OJS instance to do this. Information on how to check error logs can be found here: How do I find my PHP error log?
Best regards,
Roger
PKP Team