wrong erp base path in erp_cart

I am setting up a demo site with all contributed modules. First one I activated was erp with all submodules then this error came up:

Fatel error etc... Failed opening required 'modules/erp/erp.inc (include_path='.') in /..../sites/all/modules/erp/erp_cart.module on line 10

As you can see I copied all modules in sites/all/modules and apparently this code is still counting on the way it was done in Drupal 4.7 or before.