Help with indicator (very simple)

Hi,
I've tried everything before posting this, but I just can't make this work, even though this is the simplest of things (needless to say I'm a beginner).

I've tried to make an indicator which draws an arrow when Stochastic(5,3,2) is below 20 and begins to go up.
I import the values from the iStochastich and make a simple "If value of current period is bigger than last's then draw the arrow"...
Now I see the results (see image) and it doesn't work. The strange thing is that it's just a simple "if", and sometimes it work, sometimes it doesn't. For example, sometimes it does show the arrow when Stoch<20 and growing. But sometimes (like in this case) it doesn't.
Any help is really appreciated.
Thanks in advance.

Ok, I'm never sure about these things, but I believe you have to have a second buffer to help direct the output:
ExtMapBuffer1[i]=Low[i]-2*Point; //where you want it
ExtMapBuffer2[i]=Low[i]-3*Point; //some objects need a direction - set this one to not show on the chart
SetIndexStyle(1,DRAW_NONE,0,1);
Hope this helps, Ken

I'm sorry if I didn't understand or if I made the wrong question.
My question is:
Why if I say "Show arrow if Stoch(now)>Stoch(past)" the arrow shows when Stoch(now)<Stoch(past)
Thanks

Sorry, my mistake. The if statement looks correct. I suggest using some Print statements to see what the compare values really are - with doubles sometimes you get 20.00002 or something.

Update suggestion (better than prints): Place the indicator in a separate window, remove the arrow and display all 4 variables as lines. Use the SetIndexLabel for each line with a label. Make visible the data box. You can now see all values for each bar.

Great idea, I'll do exactly that. Thank you.

you could also post the indicator here and if someone gets a little time they could look at the code for you.