[BioC] biomaRt ensembl mmusculus does not contain all ensembl IDs (lincRNA, miRNA etc)?

[Duke]

Hi folks,

Following instruction of biomaRt usage, I am trying to get information 
for our mmu data. The code I used was below:

----------
library(biomaRt)
mart<- useDataset("mmusculus_gene_ensembl", useMart("ensembl"))
ensTransIDs <- c("ENSMUST00000000001", 
"ENSMUST00000083463","ENSMUST00000042585")
getBM(filters="ensembl_transcript_id", 
attributes=c("ensembl_transcript_id","ensembl_gene_id", 
"external_transcript_id", "external_gene_id", "refseq_dna", 
"entrezgene"), values=ensTransIDs,mart= mart)
----------

This code runs fine with some transcript_ids, but for some of others 
(for example, lincRNAs or miRNAs), it gave empty results. For example, 
the code above for one gene, one lincRNA and one miRNA produced result:

   ensembl_transcript_id    ensembl_gene_id external_transcript_id
1    ENSMUST00000000001 ENSMUSG00000000001              Gnai3-001
   external_gene_id refseq_dna entrezgene
1            Gnai3  NM_010306      14679


=> only gene Gnai3 is detected, the other two are not.

Anybody knows what I am doing wrong here, or it is just the database in 
ensembl does not contain all the available transcript_id data?

For the record, here is my sessionInfo():

 > sessionInfo()
R version 2.12.2 (2011-02-25)
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)

locale:
[1] C

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

other attached packages:
[1] biomaRt_2.6.0

loaded via a namespace (and not attached):
[1] RCurl_1.4-3  XML_3.2-0    tools_2.12.2

Thanks,

D.