Error in sending Outbound XML

Hi All,

We have an issue while sending outbound through agents.

We have an agent that recalculates cost of sell shipment. After recalculating the cost of sell shipment, we send a shipment outbound xml.

While sending the outbound we are getting the error as below:

Error in build/send XML integration for HTTPPOSTTopic: persistXML=true, guaranteedDelivery=false, externalSystem=COB.PLAN_SHIPMENT_HTTP, iMessageGid=null
________________________________________
Error writing transaction: {elementName=null} Vector index: {index=null}
________________________________________
ERROR - no Transaction object found in GLogXMLElement.
BaseBuilder.getTransactionObject()

Any clues or suggestions on what could cause such error?

Thanks,
Mahesh