Getting AppleScript function to pass string correctly

Someone please help me here and show me how to get this to work. I've checked examples on returning values from functions with this AppleScript, but something I am missing here. I'm trying to get the function, strTest(), to pass a string that will then be printed to the BBEdit editor. If I were to replace the variable with a static string, that works. But this isn't working at all. I'm getting: "The variable theText is not defined." Does anybody see what's going on?

on strTest()
	set returntest to "this is a test"
	return returntest
end strTest

tell application "BBEdit"
	set theText to strTest()
	tell window 1
		set insertionP to get selection
		set text of insertionP to (theText & (text of insertionP))
	end tell
end tell