BizTalk - SAP Send Port Error

I have a SQL -> SAP scenario in which i'm getting the following error at the Wcf-sap send port:

The messaging engine was unable to resubmit a message for send port "sp_SapReqRes_ReportsIntegration" with URL "sap://CLIENT=100;LANG=EN;@a/10.100.7.18/00?RfcSdkTrace=False&AbapDebug=False". Details:"The adapter failed to transmit message going to send port "sp_SapReqRes_ReportsIntegration" with URL "sap://CLIENT=100;LANG=EN;@a/10.100.7.18/00?RfcSdkTrace=False&AbapDebug=False". It will be retransmitted after the retry interval specified for this Send Port. Details:"System.TimeoutException: The timeout expired while trying to get a connection

Server stack trace:

at System.ServiceModel.AsyncResult.End[TAsyncResult](IAsyncResult result)

at System.ServiceModel.Channels.ServiceChannel.SendAsyncResult.End(SendAsyncResult result)

at System.ServiceModel.Channels.ServiceChannel.EndCall(String action, Object[] outs, IAsyncResult result)

at System.ServiceModel.Channels.ServiceChannel.EndRequest(IAsyncResult result)

Exception rethrown at [0]:

at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)

at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)

at System.ServiceModel.Channels.IRequestChannel.EndRequest(IAsyncResult result)

at Microsoft.BizTalk.Adapter.Wcf.Runtime.WcfClient`2.RequestCallback(IAsyncResult result)". ".

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