Thanks for the advice. I suspected this the best place to get answers (as mentioned by Tyler) because I trust several long term LuLa posters in this area, but just didn't want to ask if answers were already lurking on the net. couldn't find much on the colorsync list yet, I'll keep looking.
Error creating profile is kind of a generic message (the app needs far better error checking and reporting). I suspect you are getting bad data read in, that’s why you get the error. It would be really nice if when reading the chart, the software told you this, instead of when trying to build the profile but that’s what we have today. Why you are getting bad data read in is the question I can’t answer.
IF you are making custom targets, make them with larger patches and see if this helps. While big patches take up more paper, they can be very helpful not only in eliminating the measuring errors but provide more data (the Spectrophotometer averages X number of measurements per second).
After reading the data I almost always get an message that some colors were not what was expected, and should verify the data. Nothing looks abnormal ... no real odd colors, just density differences (as would be expected). Seems odd because I'm doing this with in i1i0 table, and on some rows the device remeasures, then tries again slower twice, and as last resort will do the row by patch (although with a rev.D device it rarely resorts to even the slower read, and never has gone to patch mode. Profiles end up with valleys and oddities, so I assume some bad data in there.
Your suggestion of bigger patches is a good one and makes a lot of sense especially considering the i1iO table... I'll try that tonight. Thx. (and my i1iO frustrations have finally peaked ... since I'm a dealer I just ordered an iSis for my store so that may help with many issues).
How are must using Snow Leopard printing targets? xRite suggests setting the Color Matching setting to Epson Color Controls, then turning off color management in the Printer Settings. The also suggest using Colorsync, but setting the profile to genericRGB. Both appear to deliver identical color to Adobe's target printing utility, so I'm assuming they are OK.