LogCategory combo-box in Enterprise Library Exception Handling Application Block.

I’ve tried to create  Enterprise Library Exception Handling Policy similar to described in Take Exception To Critical Errors With Custom Application Blocks , but I wanted to use standard Logging Exception Handler.
However the LogCategory combo-box was empty and I wasn’t able even save the configuration file due to error:”the value for LogCategory can not be null”.
It wasn’t obvious for me that I have to create “Category source“ under “Logging Application Block“ first.
It is not documented properly, a
nd I was surprised that Google returns 0 results for combination
LogCategory  “category source”