The JS file does not refresh after the update

[seaport]

I just updated my web site on an IIS Server, which is behind my office firewall (ISA server). It is an asp.net application and I can see all changes in asp.net pages from workstations inside or outside the firewall. However, an updated javascript (JS) file simply does not refresh when I view the web site outside the firewall. Even after I deleted the file, I can still access it outside the firewall. I am not sure where the problem is. So I changed the file name of the js file. After that, I can see the changes.

I believe the problem is related to ISA server because the workstation inside the firewall has no problem viewing all changes.

Any suggestions? Thanks in advance.

Seaport