What is wrong with the piece of XSLT code - xslt-1.0

Question

Just started coding. Attribute value setting does not seem to work and the child nodes of the reference node in the outer for-each loop are not accessed. I am not able to figure out what is wrong with the code.
<?xml version='1.0'?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
<B2BGatewayDoc>
<Document>
<xsl:copy-of select="/B2BGatewayDoc/Document/ServiceHeader" />
<ServiceContent>
<Transmission>
<TransmissionBody>
<xsl:copy-of select="/B2BGatewayDoc/Document/ServiceContent/Transmission/TransmissionBody/ReceiverSystem" />
<xsl:for-each select="/B2BGatewayDoc/Document/ServiceContent/Transmission/TransmissionBody/GLogXMLElement" >
<GLogXMLElement>
<ActualShipment>
<xsl:attribute name="xmlns" >
<xsl:value-of select="ActualShipment/#xmlns" />
</xsl:attribute>
<Shipment>
<xsl:copy-of select="ActualShipment/Shipment/ShipmentHeader" />
<xsl:for-each select="ActualShipment/Shipment/TransOrder" >
<TransOrder>
<xsl:copy-of select="TransOrderHeader" />
</TransOrder>
</xsl:for-each>
</Shipment>
</ActualShipment>
</GLogXMLElement>
</xsl:for-each>
</TransmissionBody>
</Transmission>
</ServiceContent>
</Document>
</B2BGatewayDoc>
</xsl:template>
</xsl:stylesheet>
XML Sample
<?xml version="1.0"?>
<B2BGatewayDoc>
<Document>
<ServiceHeader>
<Protocol name="ANSIX12">
<Sender>941714834TEST</Sender>
<Receiver>003897733SAPT</Receiver>
<MsgType>3A4MG2</MsgType>
<ReferenceNumber/>
<PipVersion>V02.02</PipVersion>
<InstanceIdentifier/>
</Protocol>
</ServiceHeader>
<ServiceContent>
<Transmission>
<TransmissionBody>
<ReceiverSystem>
<ReceiverSystemName>XXXXX</ReceiverSystemName>
<ReceiverSystemName>YYYYY</ReceiverSystemName>
</ReceiverSystem>
<GLogXMLElement>
<ActualShipment xmlns="1000181ZZZ">
<Shipment>
<ShipmentHeader>
<ShipmentGid>
<Gid>
<Xid>1000181ZZZ</Xid>
</Gid>
</ShipmentGid>
<ShipmentRefnum>
<ShipmentRefnumQualifierGid>
<Gid>
<Xid>SELLER_INV_NBR</Xid>
</Gid>
</ShipmentRefnumQualifierGid>
<ShipmentRefnumValue>VALUE 1</ShipmentRefnumValue>
</ShipmentRefnum>
<ShipmentRefnum>
<ShipmentRefnumQualifierGid>
<Gid>
<Xid>SHIP_TYPE</Xid>
</Gid>
</ShipmentRefnumQualifierGid>
<ShipmentRefnumValue>O</ShipmentRefnumValue>
</ShipmentRefnum>
<TransactionCode>IU</TransactionCode>
<TotalShipUnitCount>1</TotalShipUnitCount>
<TotalPackagedItemSpecCount>1</TotalPackagedItemSpecCount>
<CommercialTerms>
<IncoTermGid>
<Gid>
<Xid>EXW</Xid>
</Gid>
</IncoTermGid>
</CommercialTerms>
<NumOrderReleases>1</NumOrderReleases>
<VesselGid>
<Gid>
<Xid>BOL54891</Xid>
</Gid>
</VesselGid>
</ShipmentHeader>
<TransOrder>
<TransOrderHeader>
<TransOrderGid>
<Gid>
<Xid>BR20000238</Xid>
</Gid>
</TransOrderGid>
<CommercialTerms>
<IncoTermGid>
<Gid>
<Xid>EXW</Xid>
</Gid>
</IncoTermGid>
</CommercialTerms>
<TransportModeGid>
<Gid>
<Xid>H</Xid>
</Gid>
</TransportModeGid>
<ModeProfileGid>
<Gid>
<Xid/>
</Gid>
</ModeProfileGid>
<OrderRefnum>
<OrderRefnumQualifierGid>
<Gid>
<Xid>BOL</Xid>
</Gid>
</OrderRefnumQualifierGid>
<OrderRefnumValue>BOL54891</OrderRefnumValue>
</OrderRefnum>
<OrderRefnum>
<OrderRefnumQualifierGid>
<Gid>
<Xid>CUST_PO_NBR</Xid>
</Gid>
</OrderRefnumQualifierGid>
<OrderRefnumValue>4700175047</OrderRefnumValue>
</OrderRefnum>
<TotalNetWeightVolume>
<Weight>
<WeightValue>18.9</WeightValue>
<WeightUOMGid>
<Gid>
<Xid>KG</Xid>
</Gid>
</WeightUOMGid>
</Weight>
<Volume>
<VolumeValue>0</VolumeValue>
<VolumeUOMGid>
<Gid>
<Xid>CR</Xid>
</Gid>
</VolumeUOMGid>
</Volume>
</TotalNetWeightVolume>
</TransOrderHeader>
</TransOrder>
</Shipment>
</ActualShipment>
</GLogXMLElement>
</TransmissionBody>
</Transmission>
</ServiceContent>
</Document>
</B2BGatewayDoc>
The output I get
<?xml version='1.0' ?>
<B2BGatewayDoc>
<Document>
<ServiceHeader>
<Protocol name="ANSIX12">
<Sender>941714834TEST</Sender>
<Receiver>003897733SAPT</Receiver>
<MsgType>3A4MG2</MsgType>
<ReferenceNumber/>
<PipVersion>V02.02</PipVersion>
<InstanceIdentifier/>
</Protocol>
</ServiceHeader>
<ServiceContent>
<Transmission>
<TransmissionBody>
<ReceiverSystem>
<ReceiverSystemName>XXXXX</ReceiverSystemName>
<ReceiverSystemName>YYYYY</ReceiverSystemName>
</ReceiverSystem>
<GLogXMLElement>
<ActualShipment xmlns="">
<Shipment/>
</ActualShipment>
</GLogXMLElement>
</TransmissionBody>
</Transmission>
</ServiceContent>
</Document>
</B2BGatewayDoc>
Attribute xmlns is not assigned a value though the source value is availale. All nodes and tags within tag Shipment do not get created.
Any pointer to reason is highly appreciated.

Answer 1

For the formal error, Visual Studio says, An attribute with a local name 'xmlns' and a null namespace URI cannot be created. Which makes sense - you don't create namespaces like this.
Even if you could dynamically generate a namespace for your output, it would still not work because your XSL template would not be able to query the data file. In your data you have <ActualShipment xmlns="1000181ZZZ">, so all nodes under ActualShipment have the namespace 1000181ZZZ, and you have to put that namespace into your XSL. Otherwise the XSL looks for nodes with a blank namespace and does not find any -- all nodes have a namespace of 1000181ZZZ. To query that from an XSL, you would need to add xmlns:something="1000181ZZZ" to the declaration of your <xsl:stylesheet>:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:something="1000181ZZZ">
and then use it in the xPath like this:
<Shipment>
<xsl:copy-of select="something:ActualShipment/something:Shipment/something:ShipmentHeader" />
<xsl:for-each select="something:ActualShipment/something:Shipment/something:TransOrder" >
<TransOrder>
<xsl:copy-of select="something:TransOrderHeader" />
</TransOrder>
</xsl:for-each>
</Shipment>
You shouldn't be using namespaces like variables. They are supposed to be known in advance.
An obvious fix is to replace <ActualShipment xmlns="1000181ZZZ"> with something like <ActualShipment some_attribute="1000181ZZZ">.