Looks like you are many versions behind on both CF7 and WordPress. If you update your site to use the current versions of both plugins and WordPress, you shouldn’t have a problem.
The current version of the DTX requires that you use the latest version of CF7, since CF7 changes significantly with v3.6
Yeah, I have old versions as this site has been created more than 1 year ago, but I fixed this very easy. It wasn’t plugin problem, but I put wrong email address where it should be sent as I have to use smtp (moved site from linux hosting to windows hosting). Sometimes the easiest fix is the hardest if you think too much about resolving it.
Everything works pretty nice now and created new contact forms using cf7 dtx.
Glad to hear you got it sorted out 🙂