Trouble representing hours in gantt chart

Hello:

I’m having some trouble trying to represent data into a gantt chart. I’m trying to represent the % of a session a user is attending. The chart is not presenting hours properly, although it prints them ok at the tooltip. Is there anything wrong? Anybody can help me?

Thanks

As you can see in the picture, it is printing starting Date at 9h (9:02 ) aprox, while the tooltip is showing 10:02 ( the correct time).