Proxy Cache Problem

Several days ago, we have a pre-deployment simulation problem with a 3rd party tool called FckEditor. We tried to upgrade the version of the tool to higher version.
Actually in the development, we already noticed that this tool is using cache for performance when loading the files (scripts, css files, etc), but since our local will not go to proxy, we didn't have issues with this.
But after we deployed this to the staging environment, we encountered problems that sometimes it was working and sometimes it wouldn't. I tried to remove the cache-control from the header, destroy the app domain by saving the web.config, and in the end, even IIS Reset was not working.
Finally I realized that there's a proxy cache since we're using proxy servers to access the server.
In that time, I could really simulate 3 different behaviours using 3 different proxy servers when loading the tools :(
After that, we're trying hard to find out how can we reset the proxy cache, since we don't have the ability to do this, and we also can not reset the server.
But in the end, the solution is quite simple, instead of deploying the tools in the existing version folder, just deploy the tools in a new folder and then change the configuration folder settings for the tool, so we don't have to worry anymore since the cache will be retrieved from the new folder :)

PS : this idea popped out in my mind when my friend showed me that he has no problem upgrading the FckEditor at his local, he was renaming the folder name between FckEditor versions to show that it was working.