The problem I have had supporting with Veigar is my carry is way too used to supports that go in. Veigar is a peel support he counters ins and turns them around. Also don't pick Veigar with a late game ADC unless they have an ok enough early game to retaliate in an engage. Meaning Veigar can't support:
. Also don't use Veigar with people who have displacement unless you both play around that.
I had a game we stomped with support Veigar where our Jax thought I was useless but I engaged every fight with a cage and then peel for the carry with raw damage and the cage when it got back up.