Did not find function «.rowMeans»

[R [guest]]

Do anyone know why this error comes? EdgeR worked last time I tried. 

Error in mglmOneGroup(y$counts, offset = getOffset(y), dispersion = 0.05) : 
  Did not find function «.rowMeans»

 -- output of sessionInfo(): 

R version 2.14.1 (2011-12-22)
Platform: x86_64-pc-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=nb_NO.UTF-8       LC_NUMERIC=C               LC_TIME=nb_NO.UTF-8       
 [4] LC_COLLATE=nb_NO.UTF-8     LC_MONETARY=nb_NO.UTF-8    LC_MESSAGES=nb_NO.UTF-8   
 [7] LC_PAPER=C                 LC_NAME=C                  LC_ADDRESS=C              
[10] LC_TELEPHONE=C             LC_MEASUREMENT=nb_NO.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] org.Mm.eg.db_2.6.4    RSQLite_0.11.2        DBI_0.2-5             AnnotationDbi_1.16.19
[5] Biobase_2.14.0        edgeR_3.0.2           limma_3.10.3         

loaded via a namespace (and not attached):
[1] IRanges_1.12.6 tools_2.14.1  

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