CRM (V14) Error/bug Customer Group and Default Price List (Opportunity) Trasfer to Quotation

hi, i have a problem when in a Opportunity try to create a Quotation and the client have a Default Price List assigned because always assign the ‘Standard sales price list’. This is a bug/error? because the users never can change price list assigned to a client. Or how resolve this problem. If add items in opportunity again show the Standar price list and not the client price list asigned.

any sugest?