‘Correlated Random Effects - Hausman Test   
Pool: CHINA   
Test cross-section random effects   
   
Test Summary  Chi-Sq. Statistic Chi-Sq. d.f. Prob.
   
Cross-section random  0.000000 1 1.0000
   
* Cross-section test variance is invalid. Hausman statistic set to zero.   


我最近遇到这个问题，版上查了下，许多人都出现过，没有人给出合理的解释，今天终于在http://forums.eviews.com/viewtopic.php?f=4&p=6573
找到了较官方的解释，大家共勉吧，我理解应该是出现这个说明EVIEWS计算结果认为RE无效，所以选用FE吧，原文如下：
Any textbook that describes the Hausman test should help you out with the assumptions. The computation of the variance in the Hausman statistic requires that the random effects estimator be fully efficient under the null hypothesis. Specification of robust standard errors suggests, but does not impose, that you believe that the random effects estimator is not fully efficient. Hence the warning.

The reason you probably won't find any textbooks that describe this particular issue is that textbooks focus on the application of the Hausman statistic in the simplest setting...straightforward RE and FE using the conventional estimators of the coefficient covariances. It's only when you start generalizing that issues of this sort come up. I should point out that EViews will not always warn you in cases like this, it's really up to the user to understand what they are doing, but where we can, we try to help out.
我感受是大家用EVIEWS最好还是清楚检验的东西本来具体是怎么做得，才不会这么折腾。