现在开始做论文，在用Amos做区分效度时，潜变量相关系数自由估值时可以做出结果，但赋值为1时，提示出现错误“An erro occured while attempting to fit the model. Either the constraints on the parameters of the initial parameter values are bad.This erro can occur, for example, if you request a maximum likelihood solution while specifying initial parameter values that prevent the population covariance matrix form being positive definite. Check to make sure that every endogenous variable has a residual variable(error variable) associated with it”。我已经检查过每个观察变量都是有残差的。请问各位高手这是什么问题啊，要怎么补救？万分感激！！