Hi Rajesh,
Are you updating an existing form or publishing a new form?, if you are
updating an existing form then I would suggest you check to make sure no one
else has this template open when you are trying to publish your update.
If not then I would attempt to simply copy a file to the share where you
wish to publish a text file will do that will confirm if you have the correct
permissions or not to publis the template.
one last thought is that you permission to create files in the share but not
update them.