AppleScript - I get a {} when trying to separate items into categories.

on searchForSubstring(theString, theSubstring)
	try
		set oldDelims to AppleScript's text item delimiters
		set AppleScript's text item delimiters to theSubstring
		set itemsOfString to every text item of theString
		set indexes to {}
		set theIndex to 0
		repeat with X from 1 to ((count of itemsOfString) - 1)
			set theIndex to theIndex + (length of item X of itemsOfString) + 1
			copy theIndex to end of indexes
		end repeat
		set AppleScript's text item delimiters to oldDelims
		return indexes
	on error errMsg
		log errMsg
	end try
end searchForSubstring

to switchText from t to r instead of s
	set d to text item delimiters
	set text item delimiters to s
	set t to t's text items
	set text item delimiters to r
	tell t to set t to item 1 & ({""} & rest)
	set text item delimiters to d
	t
end switchText

on separateItemsIntoCategories(theContent, theCategories, categoryID)
	set newContent to theCategories
	log (count of theCategories)
	repeat with X from 1 to (count of theCategories)
		log X
		set categoryDelimiters to (item X of theCategories) & categoryID
		set categoryIndex to item 1 of searchForSubstring(theContent, categoryDelimiters)
		set newContent to switchText from newContent to "ijkl" instead of categoryIndex
	end repeat
	set oldDelims to AppleScript's text item delimiters
	set AppleScript's text item delimiters to "ijkl"
	return every text item of newContent
end separateItemsIntoCategories
try
	set theCourses to {"Appetizers", "Breakfast", "Entrees", "Soups and Salads", "Desserts"}
	set theCuisines to {"American", "Mediterranean", "Mexican", "Asian"}
	set thefile to POSIX file "/Users/Montana/Desktop/recipes.txt"
	set fref to (open for access thefile)
	set theContent to read fref
	close access fref
	set contentByCourses to separateItemsIntoCategories(theContent, theCourses, ":")
on error msg
	log msg
end try