Comments submission problem

HI
I am using the vantage premium 2.6. I had not noticed earlier but after submitting the comments on any post, Comments Text area is not being cleared and subscribers are not getting the message for moderation, giving an indication to users that comments have not been submitted.
Request you to provide the solution.
I have checked all the setting under discussions and found to be OK.
I have reinstalled the theme but is of no use.
Regards
Arun