XrmToolbBox , Ribbon Workbench - error while publish solution

Something happened!
The underlying connection was closed: 
A connection that was expected to be kept alive was closed by the server. 
Stack Trace: Error: at Xrm_Sdk_OrganizationServiceProxy$endExecute (:18445/WebResources/js/ClientUI.js:4673:13) 
at Anonymous function (:18445/WebResources/js/ClientUI.js:19527:5) at delegate (:18445/WebResources/js/ClientUI.js:2223:13) 
at $1_0 (:18445/WebResources/js/ClientUI.js:19559:70) 
Trace: Server stack trace: 
at System.ServiceModel.Channels.HttpChannelUtilities.ProcessGetResponseWebException(WebException webException, 
HttpWebRequest request, HttpAbortReason abortReason) 
at System.ServiceModel.Channels.HttpChannelFactory`1.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout) 
at System.ServiceModel.Channels.RequestChannel.Request(Message message, TimeSpan timeout)
 at System.ServiceModel.Channels.SecurityChannelFactory`1.SecurityRequestChannel.Request(Message message, TimeSpan timeout) 
at System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message message, TimeSpan timeout) 
at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, 
ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout)
 at System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall,
 ProxyOperationRuntime operation) at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)
 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 Microsoft.Xrm.Sdk.IOrganizationService.Execute(OrganizationRequest request) 
at Microsoft.Xrm.Sdk.Client.OrganizationServiceProxy.ExecuteCore(OrganizationRequest request) 
at RibbonWorkbenchAppHost.SparkleXrmBridge.ProcessExecute(String soapRequest, NameTable nt, XmlNamespaceManager prefixes) 
at RibbonWorkbenchAppHost.SparkleXrmBridge.Process(String soapRequest, String action, NameTable nt, 
XmlNamespaceManager prefixes, Action`1 callback) 


Please help me..

Thanks in advance..
Kind regards
MArtin