SwOS doesn't allow VLAN modification

[jaclaz]

Yep, VLAN 0 would be an issue. Also avoid using VLAN 1. Some devices treat VLAN 1 as something special - often with unpredictable results.

Just in case, the first two of the twelve rules of the Mikrotik Club are relevant :
http://forum.mikrotik.com/t/the-twelve-rules-of-mikrotik-club/182164/1