I am trying to use PsychSignalSentiment. But looks like the data.Get(PsychSignalSentiment) keeps retuning empty map. Does it need any approval? Can you help?

Here is the snippet. Its pretty much what is given in the document.

from clr import AddReference

from datetime import datetime, timedelta

from System import *
from QuantConnect import *
from QuantConnect.Algorithm import *
from QuantConnect.Algorithm.Framework.Selection import *
from QuantConnect.Data import *
from QuantConnect.Data.Custom.PsychSignal import *
from QuantConnect.Data.UniverseSelection import *

### <summary>
### Momentum based strategy that follows bullish rated stocks
### </summary>
class PsychSignalSentimentAlgorithm(QCAlgorithm):
def Initialize(self):
self.SetStartDate(2019, 3, 1)
self.SetStartDate(2019, 4, 1)

# Request linked news data for Apple
s = self.AddEquity("AAPL").Symbol
self.AddData(PsychSignalSentiment, s)

def OnData(self, data):
# Accessing most recent sentiment via a linked source from securities collection:
# (returns a list, you can drop the "Values" from the for loop below)
#sentiments = self.Securities["AAPL"].Data.GetAll(PsychSignalSentiment)
# Accessing unique sentiment objects via slice event:
sentiments = data.Get(PsychSignalSentiment)
# (returns a dictionary symbol-sentiment, use "Values" to enumerate below)
for s in sentiments.Values:
self.Debug(f"Bull: {s.BullIntensity} Count: {s.BullScoredMessages}")