How can I obtain degrees of freedom of LSD test that give Inf?

Question

I am performing a LSD test after getting GLMM results. My goal is to know the differences between classes (in this case the difference between grinding methods, I assayed III methods). The GLMM output obtained was called "glmer.conc.Grinding_Kit". When I apply the LSD test:

   lsmeans(glmer.conc.Grinding_Kit, pairwise ~ Grinding)

I obtained the next output:

         $lsmeans
          Grinding lsmean    SE  df asymp.LCL asymp.UCL
          I          5.26 0.323 Inf      4.63      5.90
          II         4.62 0.323 Inf      3.99      5.25
          III        4.34 0.323 Inf      3.71      4.97

         Results are averaged over the levels of: Kit 
         Results are given on the log (not the response) scale. 
         Confidence level used: 0.95 

         $contrasts
          contrast estimate    SE  df z.ratio p.value
          I - II      0.641 0.137 Inf 4.688   <.0001 
          I - III     0.921 0.135 Inf 6.826   <.0001 
          II - III    0.280 0.134 Inf 2.085   0.0930 

         Results are averaged over the levels of: Kit 
         Results are given on the log (not the response) scale. 
         P value adjustment: tukey method for comparing a family of 3 estimates

I would like to know why I obtain Inf degrees of freedom and how can I obtain a real degree of freedom. Thank you in advance.