Why won't this system work SHORT?

["Andy Dunn" <andy@xxxxxxxx>]

Here is a simple BREAK-OUT system I have been testing. It is a LONG ONLY SYSTEM

input: len(90);

  Vars:Mp(0);
  Mp=MarketPosition;
  Value0=Highest(High,len);

  Buy at Value0 Stop;

  If Mp=1 and Mp[1]=0  then
    Value1=(Highest(High[1],len) - Lowest(Low[1],len)); 

  ExitLong at Value0-Value1 Stop;

--------------------
But, when I try and make it go SHORT ONLY, the trades exit the same day or never exit? Can anyone help me reverse it?
Here is my attempt that fails??


input: len(90);

  Vars:Mp(0);
  Mp=MarketPosition;
  Value0=Lowest(Low,len);

  Sell at Value0 Stop;

  If Mp=1 and Mp[1]=0  then
    Value1=(Highest(High[1],len) - Lowest(Low[1],len)); 

  ExitShort at Value0+Value1 Stop;



Thanks