Thanks Felipe,

I thought it would be something simple like that.

I was going based on the examples in this vignette:

http://bioconductor.org/packages/release/bioc/vignettes/DeepBlueR/inst/doc/DeepBlueR.html#output-with-selected-columns

In which SIGNAL_VALUE is used, is there some way of finding out what the available column headinsg are for a given dataset so I can avoid this sort of diffficulty in the future?