Item number rule generation fails

Summary

I want to generated my item number by rule, depending on if it's an inventory item or not. When I validate my ruyle everything works, but when I try to use it I run into an error.

Content

Hello everyone,

I am trying to generate my item number with a rule, depending on wether it's an inventory item or not. I created the following rules of type assignment and association type Item Class:

1. Primary IF Expression: [Item].[Inventory].[Inventory Item] == "Yes"

Secondary IF Expression: TRUE

Return Value: auto_sequence("sequence", 200005, 1)

2. Primary IF Expression: [Item].[Inventory].[Inventory Item] == "No"

Secondary IF Expression: TRUE