title: Error : object ‘sigma’ is not exported by 'namespace:lme4'
body: <p>After updating <code>lme4 (1.1-12)</code>, I'm getting this error when I invoke <code>varComp</code> package.</p>
  
  <pre><code>library(varComp)
  Error : object ‘sigma’ is not exported by 'namespace:lme4'
  Error: package or namespace load failed for ‘varComp’
  </code></pre>
  
  <h2>Edited</h2>
  
  <p>Here is my <code>sessionInfo()</code></p>
  
  <pre><code>sessionInfo()
  R version 3.3.0 beta (2016-03-30 r70404)
  Platform: i686-pc-linux-gnu (32-bit)
  Running under: Ubuntu 14.04.3 LTS
  
  locale:
   [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
   [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8    LC_PAPER=en_US.UTF-8       LC_NAME=C                 
   [9] LC_ADDRESS=C               LC_TELEPHONE=C             LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       
  
  attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods   base     
  
  other attached packages:
  [1] lme4_1.1-12     Matrix_1.2-4    devtools_1.11.0
  
  loaded via a namespace (and not attached):
   [1] Rcpp_0.12.4         Formula_1.2-1       roxygen2_5.0.1.9000 magrittr_1.5        cluster_2.0.3      
   [6] MASS_7.3-45         mutoss_0.1-10       splines_3.3.0       BiocGenerics_0.12.1 mnormt_1.5-4       
  [11] xtable_1.8-2        colorspace_1.2-6    lattice_0.20-33     R6_2.1.2            quadprog_1.5-5     
  [16] parallel_3.3.0      broom_0.4.0         latticeExtra_0.6-28 coda_0.18-1         TH.data_1.0-7      
  [21] withr_1.0.1         MatrixModels_0.4-1  assertthat_0.1      digest_0.6.9        multtest_2.22.0    
  [26] acepack_1.3-3.3     StroupGLMM_0.1.0    phia_0.2-1          scales_0.4.0        lsmeans_2.23       
  [31] Hmisc_3.17-3        lmerTest_2.0-30     stats4_3.3.0        survey_3.30-3       munsell_0.4.3      
  [36] multcomp_1.4-4      minqa_1.2.4         plyr_1.8.3          dplyr_0.4.3.9000    stringr_1.0.0      
  [41] car_2.1-2           tools_3.3.0         grid_3.3.0          nnet_7.3-12         pbkrtest_0.4-6     
  [46] nlme_3.1-127        Biobase_2.26.0      gtable_0.2.0        mgcv_1.8-12         quantreg_5.21      
  [51] psych_1.5.8         plotrix_3.6-1       DBI_0.3.1           survival_2.39-2     gridExtra_2.2.1    
  [56] ggplot2_2.1.0       tidyr_0.4.1         nloptr_1.0.4        reshape2_1.4.1      RColorBrewer_1.1-2 
  [61] codetools_0.2-14    rpart_4.1-10        aod_1.3             memoise_1.0.0       sandwich_2.3-4     
  [66] stringi_1.0-1       estimability_1.1-1  CompQuadForm_1.4.1  mvtnorm_1.0-5       SparseM_1.7        
  [71] foreign_0.8-66      zoo_1.7-12      
  </code></pre>