Actionscript 3 :: .replace() Only Replaces First Instance?

Replace all instances of a phrase in a text string with another phrase... for some reason only the first instance is replaced and the rest ignored. I botched a solution together by running it through the string replace function around 9 times so the end result has all the <br /> replaced but I'd like to know what I've done wrong...

My Code:

var importPostAddress = "123 Fake Street<br />Mytown<br />Mycounty<br />Mycountry<br />PO5 7CD<br /><br />";
var postAddress = importPostAddress.replace("<br />",", ");

Expected result when tracing postAddress

123 Fake Street, Mytown, Mycounty, Mycountry, PO5 7CD, ,

Actual result

123 Fake Street, Mytown<br />Mycounty<br />Mycountry<br />PO5 7CD<br /><br />