asp.net - Unable to send emails through Mandrill -

i'm using mandrill api sending emails.

i'm sending webrequest send method sending emails. working fine in local. when moved code production server, i'm getting follwing error:

the underlying connection closed: unexpected error occurred on receive.  

inner exception is:

system.entrypointnotfoundexception: unable find entry point named 'enumeratesecuritypackagesw' in dll 'security.dll'.  @ system.net.unsafenclnativemethods.safenethandles_security.enumeratesecuritypackagesw(int32& pkgnum, safefreecontextbuffer_security& handle)  @ system.net.safefreecontextbuffer.enumeratepackages(securdll dll, int32& pkgnum, safefreecontextbuffer& pkgarray)  @ system.net.sspiwrapper.enumeratesecuritypackages(sspiinterface secmodule)  @ system.net.sspiwrapper.getverifypackageinfo(sspiinterface secmodule, string packagename, boolean throwifmissing)  @ system.net.security.securechannel..ctor(string hostname, boolean servermode, schprotocols protocolflags, x509certificate servercertificate, x509certificatecollection clientcertificates, boolean remotecertrequired, boolean checkcertname, boolean checkcertrevocationstatus, encryptionpolicy encryptionpolicy, localcertselectioncallback certselectiondelegate)  @ system.net.security.sslstate.validatecreatecontext(boolean isserver, string targethost, sslprotocols enabledsslprotocols, x509certificate servercertificate, x509certificatecollection clientcertificates, boolean remotecertrequired, boolean checkcertrevocationstatus, boolean checkcertname)  @ system.net.tlsstream.processauthentication(lazyasyncresult result)  @ system.net.tlsstream.write(byte[] buffer, int32 offset, int32 size)  @ system.net.pooledstream.write(byte[] buffer, int32 offset, int32 size)  @ system.net.connectstream.writeheaders(boolean async)  

my production server environment is:

os: windows server 2008 r2 standard hosting environment: iis7 

please me in resolving issue it's work stoppage me.