Check your configuration on System Properties > Database > Settings.
Did you configure any accumulators for Accumulator Field 2?
On the right side where it says Enabled, you will need to have atl east one with Acc. Field 2. For example:
Destination IP Index - Acc. Field 2
Source IP Index - Acc. Field 2
It will depend on your use case and what you are trying to do. By default, you are limited to 5 Accumulators on the ESM.