我想要在mplus 测试两个一级变量的interaction 总是显示TYPE=TWOLEVEL requires specification for the CLUSTER option 可是我已经输入了cluster=学校编码了

  USEVAR = Schoolnr TB CSE c_mccur_LKR c_Minority_birth_klasmean
  Reken_toets_klasmean SES_klasmean interC;
  DEFINE: interC = c_Minority_birth_klasmean * c_mccur_LKR;

WITHIN = TB CSE c_mccur_LKR c_Minority_birth_klasmean
  Reken_toets_klasmean SES_klasmean interC;

CLUSTER = Schoolnr;

  ANALYSIS:      
     TYPE = TWOLEVEL;

  MODEL:

%WITHIN%
TB ON c_mccur_LKR c_Minority_birth_klasmean
  Reken_toets_klasmean SES_klasmean interC;
CSE ON c_mccur_LKR c_Minority_birth_klasmean
  Reken_toets_klasmean SES_klasmean interC;
c_mccur_LKR c_Minority_birth_klasmean Reken_toets_klasmean SES_klasmean interC;
%BETWEEN%