[Plugin: Fast Secure Contact Form] How to know if my theme is causing FS contact form to not functio

I have tried many of the suggested steps in the website but I think my theme is the one causing the error. I could not receive any mail nor the theme will show the “Thank you page” before it redirects. I tried to send a test mail and it succeed. Please help me.

You can try to visit the page at http://www.davaocity.gov.ph/hrmo/?page_id=32

http://wordpress.org/extend/plugins/si-contact-form/