Enter Key in button question

Hi, I have 4 text inputs which gather 4 different series of numbers and it sent them to a outside php file when button is clicked.

I need that button to do the same thing but when the user press enter. This is the code on the button

PHP Code:

---

on (release) {getURL("http://admin.cglship.com/tracking/ts2000tracking.php", "_blank", "GET");
input = "";
input2 = "";
input3 = "";
input4 = "";
} 


---

THank you for all your help!

PHP Code:

---

on (release, keyPress "<Enter>") {getURL("http://admin.cglship.com/tracking/ts2000tracking.php", "_blank", "GET");
input = "";
input2 = "";
input3 = "";
input4 = "";
} 


---

THank, I tried that but is not working.