采用simplis语言建模时出现以下两个问题，不知道如何是好，请朋友们指点！
致谢！
F_A_T_A_L  E_R_R_O_R: Unable to start iterations because Fitted
                         Covariance Matrix is not positive definite.
                         Please provide better Starting Values.
   F_A_T_A_L  E_R_R_O_R: For a model with NY<NE or NX<NK, Starting Values must
                         be provided and NS must be set on the OU-line.