CSA 1099R software on desktop is asking for box 16a. There isn't a box 16A on my CSA 1099R from OPM

Software wont let me complete my e-file because it wants an answer I don't have.

CSA 1099R software on desktop is asking for box 16a. There isn't a box 16A on my CSA 1099R from OPM.

What do I enter?

Using Windows - TurboTax Deluxe 2024