I have a base package for the Null driver.

On the base package I have defined the following optional package for
the UA driver:

<group display-name="User Application (optional)" expanded="true">
<package display-name="UA PRD-entity" id="NF7ZCNHL_201409191450590939"

I have built all the packages and imported them into my Designer project.
I can see that the package actually has that exact Package Id.

I then drop the Null driver from the palette on the modeler workspace,
select my base package, select my mandatory feature, BUT when I select
my UA PRD-entity package on the optional features page and click next I
get the following message:

Unable to locate the following optional packages:
- ID: 'NF7ZCNHL_201409191450590939' , Name:'UA PRD-entity'

Is that because the package is aimed at another driver?

My UA package has the following constraints:

Minimum IDM version: 4.0.2
Driver types: User Application 4.0.2 Driver
User Application 4.5 Driver

Designer package development is like a black box to me.
Is there any way to enable some debugging and see what's happening?