Business rule to choose scenario based on Text3

Hi,

I am trying to create an account member formula where I have Account A divided by Account B, but the scenario in the denominator should be decided based on Text3 in the POV Scenario.

E.g. 
A#10000:S#Actual / 
A#20000:"& SourceScenario &"

SourceScenario = IF Pov.Time + 12  > Scenario Text 3, Then
SourceScenario = Forecast, Else
SourceScenario = Actual

This is how far Ive come but it is not working yet:

'Use FC as scenario if POV time is more than 12 months more than last seeded actual month in FC.
If api.Pov.Scenario.Text(3) > api.Time.AddTimePeriods(12, True) Then
DenominatorScenario = ":S#FC_WIP"
Else
DenominatorScenario = ":S#ActualL4LAtRealRate"
End If