Junction tables not getting updated with SQLBulkCopy

I have three tables like below and one company can have multiple locations

Company - Id, Name ...

Locations - Id, City, State, Country ..

CompanyLocation, Id, CompanyId, LocationId

With below code company and location tables are getting updated, but the associated / junction table is not getting updated

// Create the SqlBulkCopy object.                
using (var bulkCopy = new SqlBulkCopy(connection))
{
    bulkCopy.DestinationTableName = TargetTable;
    // Write from the source to the destination.
    bulkCopy.WriteToServer(sourceTable);
}

Any help please?