<p>. xtmixed ln_w grade age* ttl_exp tenure* || id: grade, cov(unstruct)<br/>(_xtm_setup() in lmataado, compiled by Stata 10.1, is too new to be run by this version of Stata and so was<br/>ignored)<br/>                 <istmt>:  3499  _xtm_setup() not found<br/>r(3499);</p><p>以前好像可以处理的，现在不知为什么这样了？？？高手帮助一下，谢谢！！<br/></p>