Error message hijacking my message popup.

I want to display a message to the user, letting them know why a page cannot be edited. But when I put in something like:

OnAfterGetCurrRecord()
  IF (CurrPage.EDITABLE = FALSE) THEN
    MESSAGE('some message');

Then i instead get an error message saying: "Server page is not open. Page <page name> must close." (<page name> being the previous page that runs the current page)
Note that this error only appears when I try to display a message, and when dismissed, the page displays as normal, except the message i wanted to show never appears.

Currently I have "solved" it like this:

OnAfterGetCurrRecord()
  IF (CurrPage.EDITABLE = FALSE) THEN BEGIN
    MESSAGE('');
    MESSAGE('some message');
  END;

With the empty message sort of "catching" the error, meaning both the error and my message get displayed.

Has anyone experienced something like this before?