Off topic:Problem with merge data while trying to convert gene names

Question

[mintdrink]

Hey! This is a follow-up question to one where I asked for help coding (in R) a way to convert gene accession numbers to gene names. Here is my code, where charg is a character vector of the gene accession ID's of the data set resdata:

charg <- resdata$genes
head(charg)

ensembl = useMart("ensembl",dataset="hsapiens_gene_ensembl")

theBM <- getBM(attributes='ensembl_gene_id','hgnc_symbol', 
      filters = 'external_gene_name', 
      values = charg, 
      mart = ensembl)

resdata <- merge.data.frame(resdata, theBM, by.x="genes",by.y="ensembl_gene_id")

Here's some output (where I'm struggling):

> head(charg)
[1] "ENSG00000261150.2"  "ENSG00000164877.18" "ENSG00000120334.15"
[4] "ENSG00000100906.10" "ENSG00000182759.3"  "ENSG00000124145.6" 

> dim(theBM)
[1] 0 1

> head(theBM)
[1] ensembl_gene_id
<0 rows> (or 0-length row.names)

> dim(resdata)
[1] 20381    11
> resdata <- merge.data.frame(resdata, theBM, by.x="genes",by.y="ensembl_gene_id")
> dim(resdata) #after merge
[1]  0 11 #isn't correct -- just row names! where'd my genes go?

Thank you.