how can I get three col in example counts step?

[Renfang2019]

Dear, I have been trying the chromVAR for bulk ATAC data and encourter this problem as below. Any suggestions? Thank you so much.

library(BSgenome.Mmusculus.UCSC.mm10)

example_counts <- addGCBias(fragment_counts,

•                         genome = BSgenome.Mmusculus.UCSC.mm10)
  

head((example_counts)) class: RangedSummarizedExperiment dim: 6 1 metadata(0): assays(1): counts rownames: NULL rowData names(4): score qval name bias colnames(1): E16WTc_chr.bam colData names(2): sampletype depth