"type global initialisers must be constant" help

In my current program it gives me this error. It points to the method below in my program.

	Method update_tiles()
	
		For Local i:Int = 0 To 8
		
			DrawImage tiles,t.txpos+50,t.typos,frame
			
			frame:+1
				
			If frame >= 8	 Then frame = 0
							
		Next
		
	End Method

Here is the whole code

Strict

Rem 
MapEditor Version 0.1
Author   : Amon
Compiler : BlitzMax
EndRem

Incbin "backblock.png"
Incbin "icon.png"

Graphics 800,600,16,0

tiles:TImage = LoadAnimImage("incbin::backblock.png",50,50,0,9,MASKEDIMAGE)

Global map:Int[16,12]

Global xoff:Int, yoff:Int, number:Int

number = 0

Type tile

	Global tilelist:TList = CreateList()
	
	Field xpos:Int,ypos:Int
	
End Type

Type tileset

	Global tilesetlist:TList = CreateList()

	Field txpos:Int, typos:Int
	
	Global frame = 0
	
	Function create_tileset()
		
		t:tileset = New tileset
		t.txpos = 0
		t.typos = 550
		ListAddLast tilesetlist,(t)
		
			
	End Function
	
	Method update_tiles()
	
		For Local i:Int = 0 To 8
		
			DrawImage tiles,t.txpos+50,t.typos,frame
			
			frame:+1
				
			If frame >= 8	 Then frame = 0
							
		Next
		
	End Method
	
End Type

create_tileset()		

Repeat 

	Cls
	
		For Local t:tileset = EachIn tilesetlist
	
			t.update_tiles()
			
		Next
	
	Flip
	
Until KeyHit(KEY_ESCAPE)

without running the code or putting too much thought into it, this looks like a possible cause:

Type tileset

	Global tilesetlist:TList = CreateList()

yep. That fixed it. Thanx dude :0

Amon, you might want to take a look at rockout.bmx to see how I handled this, in the 'New' method of the GravityItem type. Dunno if it's considered 'proper' in the overly strict world of OO, but it works for me!

Yes it is considered the proper way as new is the constructor of a type instance while delete is the "destructor"