Try to use
AuraUtil.FindAuraByName instead of
UnitAura.
Lua Code:
AuraUtil.FindAuraByName(ResolveName, "player", "HELPFUL")
AuraUtil.FindAuraByName works exactly same as an old
UnitAura function with querying by spell name.
I also learnt it from
zork 
-- EDIT #1
Well, I honestly can't say it works exactly same as I have not seen how UnitAura works internally, but at least it returns same outputs
