History.back not working

Hiya

I have an iFrame on my page and a swf nav bar. On the nav bar is back button to allow the user to click back in the iFrame. I managed to get this working on my mac, but its wont work on windowz. I put the following code on my back button . . . . . .

[AS]
on (release) {
getURL(“javascript:myiFrame.history.go(-1)”);
}
[/AS]

I have tried a number of different ways such as
window.myiFrame
history.back
frames.myiFrame

any ideas???