If the customer is hiding information from you. One contact person is not enough! Sales should develop relations with other LOBs to be able to investigate about the problems in the different functions. Only then they will be able to pitch for new modules/systems that would work for the customer.
Implementation complexity & customizations required by the customer.
When Integration with existing systems is not doable.
High cost. ROI must be shown to the customer to justify the cost to the management.
