Please help out a noOb

hello all,
I'm in my second day of programming lua and i need help.
I'm just doing a basic "drawing" program for my PSP trying too get better
I came form doing a similar program on 'qbasic and i cant get the screen to clear when I press R trigger Hissy Fit

in using luaplayer euphoria V8 and here is my code Blinky Smile

**************************************************
--variables
blue = Color.new(0, 0, 225)
green = Color.new(0, 225, 0)
red = Color.new(225, 0, 0)
white = Color.new(225, 225, 225)
x=100
y=100
z=0

--starting point and instructions
screen:print(x, y, "O", red)
screen:print(10, 10, "cross is blue, triangle is green, circle is red", white)
screen:print(20, 20, "and square resets the cursor", white)
screen:print(200, 200, "BY NICK COCHRAN", white)

--main program
while true do
   pad = Controls.read()

   if pad:r() then
      screen:clear()
   end

      if pad:up() and z == 0 then
         y=y-1
         screen:print(x, y, ".", red)
      end

      if pad:down() and z == 0 then
         y=y+1
         screen:print(x, y, ".", red)
      end

      if pad:left() and z == 0 then
         x=x-1
         screen:print(x, y, ".", red)
      end

      if pad:right() and z == 0 then
         x=x+1
         screen:print(x, y, ".", red)
      end

      if pad:square() then
         x=100
         y=100
         screen:print(x, y, "O", red)
      end

      if pad:triangle() then
         z=1
      end

      if pad:cross() then
         z=2
      end

      if pad:circle() then
         z=0
      end

      if pad:up() and z == 1 then
         y=y-1
         screen:print(x, y, ".", green)
      end

      if pad:down() and z == 1 then
         y=y+1
         screen:print(x, y, ".", green)
      end

      if pad:right() and z == 1 then
         x=x+1
         screen:print(x, y, ".", green)
      end

      if pad:left() and z == 1 then
         x=x-1
         screen:print(x, y, ".", green)
      end

      if pad:up() and z == 2 then
         y=y-1
         screen:print(x, y, ".", blue)
      end

      if pad:down() and z == 2 then
         y=y+1
         screen:print(x, y, ".", blue)
      end

      if pad:right() and z == 2 then
         x=x+1
         screen:print(x, y, ".", blue)
      end

      if pad:left() and z == 2 then
         x=x-1
         screen:print(x, y, ".", blue)
      end

screen.flip()
screen.waitVblankStart()
end
*******************************************************************************

plz help a noOp
PS: Ill add your name to it if you can help if you want Wink