You have to break up your calculate tags into sections with one operator each.
Calc1 = UnitOwner_GetNumDeathShards + UnitOwner_GetNumFireShards
Calc2 = Calc1 + Unit_Owner_GetNumEarthShards
Calc3 = Calc2 + UnitOwner_GetNumLifeShards
and so on.
The ONLY exception to using one operator is when you use * or / and want to inverse the second value with a - ie
Calc1 = 6 * -3