Try this one, it should work. It will disable only ONE trade after any loss, not all trades (this is what you asked, insn’t it?):

DEFPARAM CumulateOrders = false
ONCE LosingTrade = 0                   //initialize variable to allow trading
Cond = close CROSSES OVER Average[10]  //condition to buy
IF POSITIONPERF(1) < 0 THEN            //if the last one was a losing trade...
   IF LosingTrade = 0 THEN             //... and yhis is the firsr trade afterwards....
      LosingTrade = 1                  //... then disable trading
   ELSE
      Cond        = 0                  //if one losing trade already occurred do not trade and...
      LosingTrade = 0                  //... enable next trades
   ENDIF
ENDIF
IF Cond THEN                           //Buy if condition is met (unless disabled)
   BUY AT MARKET
   LosingTrade = 0                     //set variable to its initial value
ENDIF
SET TARGET pPROFIT 50
SET STOP   pLOSS   20

I have found a logic bug, because I forgot to take note that one trade had already been skipped (after being skipped) despite conditions.

So I added the variable “TradeSkipped” :

DEFPARAM CumulateOrders = false
ONCE LosingTrade  = 0                  //initialize variable to allow trading
ONCE TradeSkipped = 0                  //initialize variable to mark a trade as skipped (after a loss)
Cond = close CROSSES OVER Average[10]  //condition to buy
IF POSITIONPERF(1) < 0 THEN            //if the last one was a losing trade...
   IF TradeSkipped = 0 THEN
      IF LosingTrade = 0 THEN          //... and this is the firsr trade afterwards....
         LosingTrade = 1               //... then disable trading
      ELSE
         Cond        = 0               //if one losing trade already occurred do not trade and...
         LosingTrade = 0               //... enable next trades
         TradeSkipped= 1               //mark this trade as skipped 
      ENDIF
   ENDIF
ENDIF
IF Cond THEN                           //Buy if condition is met (unless disabled)
   BUY AT MARKET
   LosingTrade  = 0                    //set variable to its initial value
   TradeSkipped = 0
ENDIF
SET TARGET pPROFIT 50
SET STOP   pLOSS   20

It should work fine now. Let me know after testing it. Sorry for the inconvenience.

Roberto