Error during SSL Handshake with remote server

I have Apache2 (listening on 443) and a web app running on Tomcat7 (listening on 8443) on Ubuntu.

I set apache2 as reverse proxy so that I access the web app through port 443 instead of 8443. Besides, I need to have SSL communication not only between browser and apache2 but also between apache2 and tomcat7, thus I set SSL on both apache2 and tomcat7. If I try to access the web app by directly contacting tomcat7, everything is fine. The problem is that when I try to access the tomcat's web app through apache2 (reverse proxy), on the browser appears the error:

Proxy Error
The proxy server could not handle the request GET /web_app.
Reason: Error during SSL Handshake with remote server