tilemap offsets help?

ok, I've coded a little tilemap editor that uses MapStartX and MapStartY to hold where the tilemap should start on screen.

The problem I'm having is that the mouse doesnt tile up with the location of the map array and the placetile function causes an error. The full code is below with image and commented.

Strict

Graphics 1024,768,32,60

SetMaskColor 255,0,255' set the masking color

Global tiles:TImage = LoadAnimImage("pole.png",32,32,0,5)'load the tiles

Global mapstartX = 100' where the tilemap starts on the x axis
Global mapstartY = 100' where the tilemap starts on the y axis

Global map:Int[7,7]' Global array to hold map data

Global mx:Int' Tracks mousex() movement 
Global my:Int' Tracks mousey() movement

Global curtile:Int = 0'Holds the current tile number





Repeat

	Cls
	
		mx:Int = MouseX()/32*32'= set the mouse to move 32 pixels at a time
		my:Int = MouseY()/32*32'= set the mouse to move 32 pixels at a time
		
		init_map()' Call the init_map function
		draw_map()' Call the draw_map function
		place_tile()'Call the place_tile function
		
		DrawImage tiles,mx,my,curtile ' Draw the current tile at mouse&mousey locations
				
		If MouseHit(KEY_MOUSERIGHT)'If right mouse button is hit
		
			curtile:+1'Increase curtile by 1
			
			If curtile > 4 Then curtile = 0' if curtile is greater than 4 set curtile to 0
			
		EndIf
		
	
	FlushMem
	Flip
	
Until KeyHit(KEY_ESCAPE)

'the Function below sets all the map positions To 0
Function init_map()

	For Local x:Int = 0 To 6
		For Local y:Int = 0 To 6
			map[x,y] = 0
		Next
	Next
	
End Function

'the Function below updates the map and draws it to screen
Function draw_map()

	For Local x:Int = 0 To 6
		For Local y:Int = 0 To 6
			'below we draw the tiles at mapstartx and mapstarty coords of the screen
			DrawImage tiles,MapstartX+x*32,mapstartY+y*32,map[x,y]
		Next
	Next
	
End Function

'The function below places the tile on the map
Function place_tile()

	If MouseDown(KEY_MOUSELEFT)
		'Below we devide a map position by the tile size to get the correct place on the array
		map[MouseX() / 32, MouseY() /32] = curtile
		
	EndIf
	
End Function

Run this in blitzmax and you will see what I'm trying to do.