If/then/else using a greater than option

I have the  need for a script in a form to calculate between two 'fields' - look at both fields, and enter the one the is the lessor value. I have it written as such:

var a = this.getField("Text10")

var b = this.getField("Text8")

if (a.value < b.value) {

event.value = getField("Text8")}

else {event.value = getField("Text10")

}

I'm not getting any errors, just a blank field...

(and yes, text8 and text10 fields have data) :-)

I'm a novice regarding javascript, so any help would be appreciated.

Thanks!

Jill

- using Adobe Acrobat 9 Pro on MAC lion