Pareto Chart.. almost there just missing something

Hi All,

I am very close to achieving a successful pareto chart however i am missing something and it is causing a problem for me.

Here is my data:

What I am trying to achieve is a pareto chart to show the duration hours vs the room number.

The DAX for TotalAmount =  SUM(ENGINEER_TABLE[DURATION_HOURS])

The DAX for Cumulative Percent = [DURATION_HOURS] / [TotalAmount].

Here is the graph at the minute:

As you can see it is calculating the percentage total correctly... however why is it not to 100 percent at the right hand side?

Please help, Thanks!