Hi Chetan,
Thanks for giving us feedback regarding the issue caught by you since it helps us to improve the plugin.
We have made few changes in the code of plugin to resolve the issue.
Try installing updated version(0.1.5) of the plugin and let us know if still there is any problem.
Some more features have also been added in the new version of the plugin, you can refer changelog of the plugin page for more details.
Please reply if the updated plugin helps you that we can mark this topic as resolved.
http://wordpress.org/extend/plugins/product-enquiry-for-woocommerce/
Cheers !!!
Thanks,
WisdmLabs