Inadequate information under uncertainty is indispensable to multiattribute analysis, which can be well handled by the Evidential Reasoning Approach. The factors which bring about influence on the belief of the inadequacy in the assessment results were studied, including the belief of the inadequacy in the rules as input, the weights and the consistency of the rules. The domain of the inadequacy in the assessment results was determined and a preliminary result was drawn: the belief of the inadequate information in the assessment result can be less than the bigger one of the belief of inadequate information in the rules as input, but may not be more than the smaller one of the belief of inadequate information in the rules as input. The logical and geometry meaning of consistency of the rules was illustrated. The link between the consistency of the rules and the concept of “degree of conflict” was studied. 