All Abra transactions are verified by the blockchain - that's how we ensure that the money you're sending is yours to send. It's one of the ways we prevent fraud in the system.
It can take up to 30 minutes (usually less) from the time digital money gets transferred to the time this transaction is verified. Until Abra gets verification that the transaction is a valid and unique one, you won't be able to send or withdraw the funds in your Abra wallet.
If you continue to experience trouble, please let us know at [email protected].