Writing and if then else statement

I know this is a lot easier than I'm making it, but I've been trying to figure out the correct syntax all afternoon.

I have a table with 15 rows, if the column Change15 is = R, then I want column FarmDes15 to be visible

Any other value I want it to be invisible.

I have...

if ($.boundItem(xfa.event.newText) == "R") {

  this.resolveNode("FarmDes15").presence = "visible";

} else {

  this.resolveNode("FarmDes15").presence = "invisible";

}

which works, but whenever I choose a value for Change, it clears out all the other fields on the form.

Please help if you don't mind.

Thanks