PeriodHighLow Tradestation indicator Help

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Hello;

Preface this with I am a newbie at Tradestation development. I am trying to write some simple indicators and then grow from there, and I am needing some assistance with the seasoned professionals could lend some help.

 

I have an basic indicator I am working on, that will calculate the highest high, or lowest low within a given time frame. I have the following:

 

Inputs:    Starttime (0800),
        EndTime ( 1000);
        
        
Vars:    PeriodHigh(0),
        LastPeriodHigh (0),
        PeriodLow(999999),
        LastPeriodLow (999999);
        
If T >= Starttime and T <= EndTime then
Begin
    If H > PeriodHigh then PeriodHigh = H;
    If L < PeriodLow then PeriodLow = L;
    End;
    

Plot1 (LastPeriodHigh);
Plot2(LastPeriodLow)
 

However it appears when i apply the indicator to the chart, it is plotting the session high and low, but NOT from the range of times i am using... Not sure why?

 

if anyone could help out, and explain what I might be missing here.