"I am able to successfully hit the post call survey from the main script."
Do you mean, from the Agent? The flow should be:
1) Caller to Script 1
2) Caller to Agent
3) Caller to Script 2
It looks like in Script 1, you're trying to store values in Enterprise Data, while in Script 2, you're trying to read Session data. That wont work, because the two features are distinctly different. You will need to pick one, and do that one thing in both Scripts.