Query nodes of an xml document - Visual Basic

[cena29]

I have an XML document that Im trying to read but my query keeps returning no result. the query im using is...\[code\] Dim products = From product In doc.Descendants("DeviceInstance") _ Select product.Attribute("ProductRefId").Value For Each result In products MessageBox.Show(result.ToString()) Next\[/code\]where am I going wrong??see below for xml\[code\] <?xml version="1.0"?> <KNX xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" CreatedBy="knxconv" ToolVersion="4.0.1004.62808" xmlns="http://knx.org/xml/project/10"> <Project Id="P-0225"> <Installations> <Installation Name="" InstallationId="0"> <Topology> <Area Id="P-0225-0_A-734" Name="East" Address="1" Description=""> <Line Id="P-0225-0_L-736" Name="Ground" Address="1" MediumTypeRefId="MT-0" Comment="" Description=""> <DeviceInstance Name="" Id="P-0225-0_DI-761" ProductRefId="M-0064_H-MTN647893-1-O000C_P-MTN647893" Hardware2ProgramRefId="M-0064_H-MTN647893-1-O000C_HP-480B-21-4CB2-O000C" Address="5" Comment="" LastModified="2012-07-04T19:27:44" LastDownload="2012-08-22T11:27:40" InstallationHints="" IndividualAddressLoaded="true" ApplicationProgramLoaded="true" ParametersLoaded="true" CommunicationPartLoaded="true" MediumConfigLoaded="true" Description="SWA1101" IsCommunicationObjectVisibilityCalculated="true"> <ParameterInstanceRefs> <ParameterInstanceRef RefId="M-0064_A-480B-21-4CB2-O000C_P-1_R-1" Value="http://stackoverflow.com/questions/12583094/0" /> <ParameterInstanceRef RefId="M-0064_A-480B-21-4CB2-O000C_P-2834_R-2834" Value="http://stackoverflow.com/questions/12583094/0" /> <ParameterInstanceRef RefId="M-0064_A-480B-21-4CB2-O000C_P-2835_R-2835" Value="http://stackoverflow.com/questions/12583094/0" /> </ParameterInstanceRefs> <ComObjectInstanceRefs> <ComObjectInstanceRef RefId="M-0064_A-480B-21-4CB2-O000C_O-31_R-243" IsActive="true"> </ComObjectInstanceRef> <Connectors> <Send GroupAddressRefId="P-0225-0_GA-128" /> </Connectors> </ComObjectInstanceRef> </ComObjectInstanceRefs> </DeviceInstance> </Line> </Area> </Topology> </Installation> </Installations> </Project> </KNX>\[/code\]