If you are using DX 1-Man and getting the below error:
DX 1-Man error: (1) (F014) Invalid ConsignmentReference2 length.
This means that the order reference or customer reference is more than 12 characters. If it's possible to adjust the number of characters coming from your store/channel, then that's one of the options you can take.
If you want to continue using the reference format you have, you'll have to let us know so we can contact DX and ask them to increase the number of characters allowed. They said they are able to increase the limit up to a maximum of 100.