[R] Repeated Measure ANOVA-Old question

[ctu at bigred.unl.edu]

Hi R users,
I google the website and I found that there are three ways to perform  
repeated measure ANOVA: aov, lme and lmer.
http://www.mail-archive.com/r-help@stat.math.ethz.ch/msg58502.html
But the questions are which one is good to use and how to do post-hoc test?

I use the example that is provided in the above link and I try
> tt<-aov(p.pa~group*time+Error(subject/time),data=P.PA)
> TukeyHSD(tt)
Error in UseMethod("TukeyHSD") : no applicable method for "TukeyHSD"

Any suggestions?

Appreciate in advance~
Chunhao