Function IMPORTRANGE is not updating

I want to use the IMPORTRANGE function every time I open one spreadsheet so this opened spreadsheet can be synchronized with another spreadsheet. So, in A1, I put a call formula like this:

=importrange("0AmEr9uNtZwnNdDFKMTVlbmZYZ3ZyOWM0aXpZS2twM1x";  "myData!A1:W384")

But this IMPORTRANGE call remains static. That is, once imported, the data isn't updated when the imported sheet is changed.

So what is wrong? I wonder if I can use IMPORTRANGE, a spreadsheet function, within a Google Apps Script (which is like JS code).

How can I call a spreadsheet function inside a script?