Hi Afarag ,
Since you have not posted a link to the post from where you got the details for making this chart , I will request you to do some troubleshooting yourself.
Since the chart has only two series , which are defined as follows :
=SERIES("Centre",Sheet2!$I$4,Sheet2!$J$4,2)
=SERIES("Needle",Sheet2!$I$4:$I$5,Sheet2!$J$4:$J$5,1)
and there is only one chart in the construction , all you need to do is first establish if this construction will actually do what you expect it to do.
The only locations which are relevant to moving the needle are I4 , I5 , J4 , J5.
Forget the equation , and just put values in these 4 locations , and see how the needle behaves ; unless you can find that the needle moves smoothly from the minimum value of say 0 , clockwise till the maximum value of say 100 , there is no point in doing anything else.
If you find that for any value of these 4 locations , you are not able to move the needle properly , please post a link to the page from where you got the details for this chart.
Narayan