Digital BW, The Print

I am thoroughly baffled by the following.  I am trying to take spot measurements with a 
Gretag i1 Photo device (as part of taking a look at making curves for QTR).  I am using the 
Measure Tool (part of Profilemaker Pro 4.1.5).  When I use Spot I with XYZ selected as my 
colour space I am getting weird Y values, eg 55 for the 100 step wedge.  If I measure the 
21 strip using chart and run it through Roy's calc-density I get sensible Y and density 
values, eg 2.62 for Y at 100, from the same patch.  Am I just missing something obvious 
here or is the i1 on the blink?