[TYPO3] extension Development, reuse another module in own extension

[Andreas Jonderko]

Hello!

Im developing an BE-Extension for Synchronizing / Importing 
functionality for the Commerce Extension and I want to reuse the 
Category-View-Frame that is used in Commerce in my own module, So I can 
show the results to the users after the synchronize-process.

Im adding my module directly under the commerce with:
	t3lib_extMgm::addModule('txcommerceM1','commercesynchronizeM1','bottom',t3lib_extMgm::extPath($_EXTKEY).'mod1/');

It works well, and I see a blank white frame between my module and the 
left frame... Now I added the line:
	t3lib_extMgm::addModule('txcommerceM1','category','',t3lib_extmgm::extPath('commerce').'mod_category/'); 

To add the Category-List module too, but it does not show up... what do 
  forget?

Here my Module-Config:

define('TYPO3_MOD_PATH', '../typo3conf/ext/commerce_synchronize/mod1/');
$BACK_PATH='../../../../typo3/';

// register this on the commerce module with the name commercesynchronizeM1
$MCONF['name']='txcommerceM1_commercesynchronizeM1';
	
$MCONF['access']='admin';
$MCONF['script']='index.php';

$MLANG['default']['tabs_images']['tab'] = 'moduleicon.gif';
$MLANG['default']['ll_ref']='LLL:EXT:commerce_synchronize/mod1/locallang_mod.xml';