Web Service Authentication

   I am attempting to add a Web Service for an application.  When I try and get a DataSet (mWebService.GetContactsDataSet(q, String.Empty);) it fails. 

I have tried tracing the error but it does not create the error on my code it creates it after leaving Login in the LoginManager.

Soap Detail Error Message:"<Exception name=\"IdeaBlade.Persistence.PersistenceServerException\" message=\"Object reference not set to an instance of an object.\" operationType=\"Login\" failureType=\"Other\" />"

Stack Trace:"   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)\r\n   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)\r\n   at LOC.CEMS.Webservice.Tests.CEMSWebservice.WebService.GetContactsDataSet(Query pQuery, String pDataSourceExtension) in C:\\Development\\CEMS\\NUnitTests\\LOC.CEMS.Webservice.Tests\\Web References\\CEMSWebservice\\Reference.cs:line 296\r\n   at LOC.CEMS.Webservice.Tests._Default.Page_Load(Object sender, EventArgs e) in C:\\Development\\CEMS\\NUnitTests\\LOC.CEMS.Webservice.Tests\\Default.aspx.cs:line 39\r\n   at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)\r\n   at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e)\r\n   at System.Web.UI.Control.OnLoad(EventArgs e)\r\n   at System.Web.UI.Control.LoadRecursive()\r\n   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)"

Help would be greatly appreciated.

Environment:
Webservice is a project in the solution. Created test web site app, added to solution, to call the web service.

Code:

mWebService = new CEMSWebservice.WebService();

LoginCredential credential = new LoginCredential();
                credential.Username = "admin";
                credential.Password = CryptoFns.MD5HashUTF16ToString("password");
this.mWebService.Security = new SecurityHeader();
this.mWebService.Security.UsernameToken = credential;

Query q = new Query();
QueryClause clause = new QueryClause();
clause.ColumnName = "InActive";
clause.ColumnValue = "False";
q.Expressions = new QueryExpression[] { clause };

this.mResultsGrid.DataSource = mWebService.GetContactsDataSet(q, String.Empty);