{ User Inputs }
multi:=Input("ATR multiplier",0,10,2.5);
pds:=Input("ATR periods",1,252,10);
pds1:=Input("ATR lookback periods",1,252,21);
plot:=Input("[1]Trailing Stop, [2]Long+Short, [3]Signals",1,3,1);
adv:=Input("plot: today's trailing stop=0, tomorrow's stop=1",0,1,0);
delay:=Input("Entry and Exit signal delay",0,5,0);

{ Trailing Stops }
StLong:=HHV(C-multi*Mov(ATR(1),pds,E),pds1);
StShort:=LLV(C+multi*Mov(ATR(1),pds,E),pds1);
stopLong:=If(C<PREV,StLong,Max(StLong,PREV));
stopShort:=If(C>PREV,StShort,Min(StShort,PREV));

into the "Sell Order" tab. I keep getting an error stating "This function is not allowed 
in this type of formula." The cursor then blinks in front of "Input ("ATR multiplier",0,10,2.5);

Would somebody please give a newbie a hand? 

Thanks

Thanks. Then it appears most of that code is unnecessary. Is this all I need to trigger a sell?

multi:=2.5;
pds:=10;
pds1:=21;
{ Trailing Stops }
StLong:=HHV(C-multi*Mov(ATR(1),pds,E),pds1);
C<StLong;

I feel I'm missing something in this line I left out:
"StopLong: = If(C<PREV,StLong,Max(StLong,PREV));"

Correct me if I'm wrong,
If C<Prev, then StopLong=StLong
If C>=Prev, then StopLong= the greater of StLong and Prev. Does this "Prev" apply to StLong or StopLong? I just can't understand why I need this line.