Error when importing funds from another address

I have been trying to import NVO tokens linked to my wallet, into Counterparty. After much effort, I managed to find my blockchain private key by using a program to convert my mnemonic phrase. Upon entering my private key into counterparty, it manages to find the tokens I want to import (NVST, NVOT) but when it tries to sweep them it comes back with an error (after about 5-10 minutes of waiting). Can anyone help?