Differentiating points by category in logistic plot

Greetings,

I've got a simple logistic plot, not unlike this one http://www.sas.com/images/sascom/2008q2/jmp_new_lrg.jpg

except that all of my points, whether above or below the curve, look exactly the same, whereas in the above image the points below the line are nice red dots and those above the line are nice blue +'s. For the life of me I can't figure out how to persuade JMP (8.0.2, Mac) to differentiate the two categories of data like this.

Any suggestions would be greatly appreciated!

Thanks,

Alan