KPI histogram bars not centered

Hi all,

A colleague tried to make a KPI categorizing the flows by the numbers of the steps they contain, as seen below :

I suggested to dedicate a color to each colums using a SQL Query that return this kind of result (we do not work on the same database and in mine there are only 2 categories not 5) :

And his UI page gives him this result :

How can I modify my query to center the bars ?

Thank you in advance,

Pierre TRAMALONI