R importing XML missing empty columns

I'm attempting to import a XML file of row column data (from a data recorder) using R. I have tried using the XML package and the following code...

# XML package
require(XML)

# Read the data
InputFl<-"MyFile.xlm"
InptDt<-xmlToDataFrame(InptFl)
names(InptDt)

This imports (most of) the data successfully to a data.frame but excludes columns (which have a header) but where all values are null (I can see these columns when I import to file to Access using that XML importer).

I experimented with...

InptDt<-xmlTreeParse(InptDt, ignoreBlanks=TRUE)
str(InptDt)

This approach seem to parse all fields in parsed object (I can seem them in the file structure) but I'm not sure how to parse this object as a data.frame?