A consultation about DF of the result of lmer

Dear, 
I am a graduated student who's topic is  ecology. Recently, I am studying how to establish a liner mixed model to exclude the error caused by the difference of site by using lme4 in R. I found  when I calculated p value by using the function of "Anova" of car package the Df is 1. But in fact the data set has 6 levels. Then I also operate according to the code of reference PDF of lme4 in P52(lmer) without any change. When run "anova(fm1, fm2)" I found the Df of fm1 also is 1. As I see if the Df is wrong the p value would be wrong either. I want to know how to correct my wrong. I will very appreciate your reply.


Best regards,
Rumeng He