Deployed schema not being found by XmlReceive pipeline

Hi,

 I have several applications all working okay on a dev box, but one insists that the schema is not deployed, even though the namespace and root element match exactly, and the assembly is GACed okay.

I have downloaded a tool called SchemaDetector (http://www.digitaldeposit.net/blog/2006/12/detector-tool-for-biztalk-development.html) that uses the BizTalk object model to check the schema can be located by namespace and root element and the tool reports the schema is there.

 However, for this one particular message, the receive location fails to match the XML message to the schema:

Event Type: Error
Event Source: BizTalk Server 2006
Event Category: BizTalk Server 2006
Event ID: 5753
Date:  13/11/2007
Time:  10:50:14
User:  N/A
Computer: VADER
Description:
A message received by adapter “SQL” on receive location “G4S.BPREnablement.ESS.SQL.GetMessagesExpenseClaims” with URI “SQL://VADER/ESS/EXPENSE-CLAIM” is suspended.
 Error details: There was a failure executing the receive pipeline: “Microsoft.BizTalk.DefaultPipelines.XMLReceive, Microsoft.BizTalk.DefaultPipelines, Version=3.0.1.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35” Source: “XML disassembler” Receive Port: “G4S.BPREnablement.ESS.ExpenseClaim” URI: “SQL://VADER/ESS/EXPENSE-CLAIM” Reason: Finding the document specification by message type “http://schemas.g4s.com/ess/sqlgetmessages/v3_0#Interface_Out” failed. Verify the schema deployed properly.  
 MessageId:  {0434E48B-F243-4310-89CC-30D19AB1C7A8}
 InstanceID: {3FEE00EC-1C35-4F97-AC31-5D0C4AD6D10B}

Anyone any idea what has happened to BizTalk to prevent the XML message from working.  Other messages against similar schemas work perfectly.

If I set AllowUnrecognizedMessage to True on the XMLReceive pipeline, the message enters the Orchestration, but later (on a send back to the MessageBox), BizTalk blows up with an internal error:

 [7776] Global error situation: System.ArgumentOutOfRangeException: Index and length must refer to a location within the string.
[7776] Parameter name: length
[7776]    at System.String.InternalSubStringWithChecks(Int32 startIndex, Int32 length, Boolean fAlwaysCopy)
[7776]    at Microsoft.XLANGs.Core.InvalidPropertyValueException..ctor(XmlQualifiedName name, Object val, Exception inner)
[7776]    at Microsoft.BizTalk.XLANGs.BTXEngine.BTXXlangStore.PrepareMessage(XLANGMessage msg, IList promoteProps, IList toPromote)
[7776]    at Microsoft.BizTalk.XLANGs.BTXEngine.BTXXlangStore.WriteMessageState(XLANGMessage msg, Segment seg, IList promoteProps, Boolean track, IList toPromote, Boolean ignoreRoutingFailure)
[7776]    at Microsoft.BizTalk.XLANGs.BTXEngine.BTXDirectPortBinding.SendMessage(XLANGMessage xmsg, XlangStore store, Segment seg, OperationInfo op, IList additionalProps, IList toPromote, Boolean ignoreRoutingFailure)
[7776]    at Microsoft.BizTalk.XLANGs.BTXEngine.BTXPortBase.SendMessage(Int32 iOperation, XLANGMessage msg, Correlation[] initCorrelations, Correlation[] followCorrelations, Context cxt, Segment seg, ActivityFlags flags)
[7776]    at G4S.BPREnablement.BizTalk.Orchestrations.ESS.ExpenseClaimDispatcher.ExpenseClaimDispatcherOrch.segment2(StopConditions stopOn)
[7776]    at Microsoft.XLANGs.Core.SegmentScheduler.RunASegment(Segment s, StopConditions stopCond, Exception& exp)

Anyone here suggest a way to find out why BizTalk won’t find the correct schema or how to get out of this mess it seems to be in!

Thanks in advance.