Offset Stacked Bar Chart

[#1]

Dear Community,

I'm trying to create a stacked bar chart that displays task activity by user over a working day. I have had previous help in the below thread but haven't found a solution.

http://community.qlik.com/thread/148292

My current graph is as below:

As you can see there are a couple of tasks that appear as negatives. These tasks are taking place during the working day and aren't extremes - can anyone (using my formulas in the previous thread) see where I am going wrong?

Many thanks,

Drew