Using version 5.0.5 of Dominos, for reference, patch 5.0.4 of WoW.

Problem's fairly simple, at least to describe. No vehicle action buttons. Got the vehicle bar showing up and horribly placed (though that's Blizzard's fault really) with micro menu and dismount buttons showing just fine, but no action buttons. Problem is the same even with just Dominos (literally just, even options were disabled) enabled. Had the error below thrown when getting on the vehicle (Aviana's Guardian in the Vigilance on Wings quest, if for some bizarre reason it's vehicle specific)...

Message: Interface\FrameXML\RestrictedExecution.lua:397: Call failed: Interface\FrameXML\RestrictedFrames.lua:659: Invalid snippet body
Time: 08/29/12 11:45:08
Count: 1
Stack: C: ?
Interface\FrameXML\RestrictedExecution.lua:397: in function <Interface\FrameXML\RestrictedExecution.lua:390>
(tail call): ?
(tail call): ?
Interface\FrameXML\SecureHandlers.lua:113: in function <Interface\FrameXML\SecureHandlers.lua:108>
C: in function SetAttribute' Interface\FrameXML\RestrictedFrames.lua:444: in functionSetAttribute'
[string " self:GetFrameRef('header'):SetAttribute('s..."]:1: in function <[string " self:GetFrameRef('header'):SetAttribute('s..."]:1>
(tail call): ?

Interface\FrameXML\RestrictedExecution.lua:441: in function <Interface\FrameXML\RestrictedExecution.lua:412>
(tail call): ?
...
Interface\FrameXML\RestrictedFrames.lua:312: in function `Show'
[string " local newstate = newstate or 'normal'..."]:11: in function <[string " local newstate = newstate or 'normal'..."]:1>
(tail call): ?

Interface\FrameXML\RestrictedExecution.lua:441: in function <Interface\FrameXML\RestrictedExecution.lua:412>
(tail call): ?
Interface\FrameXML\SecureHandlers.lua:113: in function <Interface\FrameXML\SecureHandlers.lua:108>
C: in function `SetAttribute'
Interface\FrameXML\SecureStateDriver.lua:114: in function <Interface\FrameXML\SecureStateDriver.lua:95>
Interface\FrameXML\SecureStateDriver.lua:127: in function <Interface\FrameXML\SecureStateDriver.lua:119>

Locals: (*temporary) = "Call failed: Interface\FrameXML\RestrictedFrames.lua:659: Invalid snippet body"

This should be resolved with 5.0.7.