The request was aborted: Could not create SSL/TLS secure channel for HttpWebRequest

I am using an asmx webservice client to connect to a backend web service and we have multiple environments .In one of the server ,am getting error “The request was aborted: Could not create SSL/TLS secure channel” but every other environments it works fine. I referred below articles already and none of it helped.

Optional parameters in ASP.NET web service

I have a ASP.NET web service. This web service works fine. However, the WSDL lists some parameters as optional (minoccurs = 0) and others as non-optional. Some of the optional parameters are actually not optional, others which are marked as non-optional are actually optional. I would like to fix this, but I can’t find the location where this information is coming from.