callPlugin() can only be used from within scripts started by the plugin (the DLL) itself. That's what the means with "If the running script is executed from within a Plugin, you can callback the native part of the plugin using this function."
So callPlugin() is a sort of a bridge that allows the scripting part (ECMAScript or JavaScript) to pass parameters to the native part (eg. C++ part) or to start a function there. For the other way round, the native part will use .
However, to your problem: What you want to do, is a communication between two different scripts (your plugin and the skin). For this purpose, you have to export a function in the first script, which can then be called from the second script.
Please use the functions and for this purpose.
The export is needed, as different scripts run completely independent by default.
Hopefully, our explanation is not too confusing so that you can get the idea now
Best regards,
Your Silverjuke Team
PS: Weasel and Erik: Welcome aboard!