Script looks fine to me. I'd suggest taking k_ptat17_enter, renaming that to something, and then adding
ExecuteScript("WHATEVER_YOU_NAMED_THE_OTHER_SCRIPT", OBJECT_SELF, -1);
to the end of your script.
You'll run into compatibility issues with other mods that edit the on enter script, but those are few and it's relatively easy to fix on a case by case basis.
Also I don't think this matters, but if it does matter I might as well tell you:
That's the function I usually use to check if an object is valid. I think your way should work, but just in case it doesn't, you know.