Error: Alfresco lookup for one and only class

Hi,

I don’t sure if it’s a CMDBuild’s bug or it’s my fault.

  1. I make a custom lookup for Alfresco categories to use at one class: “AlfrescoPrueba”
  2. I select the new lookup for that class.
    alfrescoprueba
  3. The new lookup values appears on attachment category combo;
    combo
  4. But when I save it, CMDBuild shows this error and crashes

In configuration system section, I can change “by default value” with other lookup. This option runs OK; but not If I change the class propierties and select a specific lookup for attachments

Thanks in advance.