Disconnected Agent after update TeamCity Server SSL certificate

Hi All,  We use TeamCity 7.1.5. I updated TeamCity Server site certificate ( replaced server.p12 file with new one) for new time period and TeamCity Server lost connection with single Agent. Agent status is Disconnected, Authorized, Enabled. With WEB Browser I navigated to TeamCity site and made sure new certificate is valid.  Into teamcity-agent.log file I see many simular messages, for sample: [2014-03-20 16:37:11,694]   WARN -    jetbrains.buildServer.AGENT - Ping problem: Call https://oursite/RPC2 buildServer.ping: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target   How I can fix this Agent connectivity problem with new certificate?  With old site certificate TeamCity worked properly.
Thank in advance,    Shimon
P.S. I see difference in Details of old and new certificate. Old Certificate Signature Algorithm  is PKCs #1  SHA-1  With RSA Encryption.  New Certificate Signature Algorithm  is PKCs #1  SHA-256  With RSA Encryption.

Message was edited by: Shimon Shtrafun