Hi Alejandro,
While defining BOE system in /CRYSTAL/RPTADMIN, maintain SAP Role in Role Tab not the custom Role (Z*). Check whether Crystal Reports and queries associated with it are assigned to that SAP Role.
GoTo:
TCode: SU01, Add SAP Authenticated User's and Assign Roles of which Crystal Reports and its corresponding queries has been mapped with SAP eg: SAP Role : SAP_BW_FIN_CR.
TCode: PFCG (Role / Menu Statistics Creation / Modification)
SAP Role: SAP_BW_FIN_CR and Customize the Menu Structure as per the Business Requirement
Please also refer the below threads:
http://help.sap.com/erp2005_ehp_06/helpdata/en/32/1ee99a4aa944dc832de12c45866611/frameset.htm
http://scn.sap.com/docs/DOC-28918
Hope this information helps you to some extent...
--Raji. S