Bizarre display issues

[ayuk23]

Hey I love your pie chart, but am having a few difficulties using it. The display will work sometimes and look great, however other times when we navigate to the screen with the view, the simulator displays this.

Here is a screenshot of the view selected in our storyboard:

It seems like when it works, so long as we do not modify the project, it will always work. However making small changes to the app in areas that aren't related to the display of the chart can cause it to be displayed incorrectly. Do you have any idea why that may be?

Thanks in advance,

Andrew