[TYPO3-extbase-kickstarter] Using "Extend existing model class" feature with TYPO3 6.0

[Roland]

hi everybody,

my setup:
++ TYPO3 6.0.1
++ EXT:extension_builder 2.5.1
++ EXT:acme_test to reproduce my problem

i unsuccessfully try to use the "Extend existing model class" feature in 
EXT:extension_builder to extend a class "Oragnization" with a class 
"Company" and run into this error message on saving:

--- quote ---

Extension could not be saved: Table definitions for table 
acme\acmetest\domain\model\organization could not be loaded. You can 
only map to tables with existing TCA or extend classes of installed 
extensions!

--- /quote ---

i filled the field "Extend existing model class" with this:

ACME\AcmeTest\Domain\Model\Organization

have i done something wront, or could this be a bug?

you can download the test-extension here:

https://www.dropbox.com/s/q1vpfpbuw9pz1bb/acme_test.zip

kind regards

roland