Sales Order configuration not possible

Hi Friends

I created sales order with reference to Quotation for two material A and B, when i save it, it shows document incomple error. When i click on edit, screen display Item A - Configuration and Item B - Configuration. When i click on complete, system display further error screen "Configuration not possible for material A " and next blow line reason 3 -> help, similarity for material B also.

Friend how this problem can be solved.

Dave