Adobe script not working for some users

Hi.  I have a script for conditional formatting to change the text to red if it is NOT equal to another field.  It works if I use it, but 2 other people have tried to use it and the text always shows red for them even if it is equal to the other field.  Can you tell me if something needs to be changed with the code below?

if(event.value != this.getField("ri1").value && event.value == ""){
event.value = "0";
}

if(event.value != this.getField("ri1").value){

event.target.textColor = color.red;}

else {
event.target.textColor = color.black;}