Dear sruthi
Dangerous Goods Content Management is one of the key functionality In SAP Transportation Management component. For loading DG Content in to TM system seems you are transferring the data from EHS-DG Master. here you have one more option for Loading DG Content by using Data provider SERC tool ,which you can download the data from service market place and upload in to TM by using content loader
The content comprises dangerous goods (DG) regulations, regulation texts (for example, substance names), phrases, and the required Customizing data. Based on the content, the content loader generates DG master data records in SAP TM.
The content loader is particularly useful if you do not have the required master data for dangerous goods in your SAP TM system. For example, if you are a logistics service provider (LSP) who receives dangerous goods data from shippers. You can use the generated DG master data records as templates for document-based dangerous goods records and as the basis for consistency checks (for example, to check whether a shipper has provided the correct temperature data for the corresponding UN number).
Coming to your issue seems it is due to non compatable external number range in SAP TM , change the external number range customization in TM and import the phrases again.
Balajee