So it looks like your issue is when you have 0 values on your x-axis you're getting:
- Null appearing in your tooltip's x-value label
- An incorrect value appearing in your tooltip's y-value label
Is that a correct understanding of your issue? If so, we fixed a couple of bugs in recent releases that might be related. So it might be worthwhile checking which version of our framework your app is using by logging it (using NSLog(@"%@", [ShinobiCharts getInfo]) - I'd recommend doing this just so we can be sure Xcode isn't accidentally linking against an older version. Once you've done that could you please post the version that is logged so I can check that against our recent fixes?
If your response from the above confirms that you're on the most recent release then we must be dealing with an unfixed bug that we're not currently aware of. In order to proceed we're going to need to be able to debug what's happening in order to fully understand the problem. I tried taking the ColumnSeries sample bunbled with our download and modified the data to include 0s on the x-axis, but this failed to recreate the issue you have described (the tooltip succussfully shows the correct x and y values).
I can see your thread title mentions a custom crosshair, so there's possibly something going wrong there, or it could be related to some edge case you've found specific to your chart/axis configuration. The best way to get a reproducible example of this issue to us would be to take the ColumSeries and adapt it till it shows the undesired behaviour (this might include your custom crosshair). Feel free to send this to firstname.lastname@example.org with a link to this forum thread (so we can match it up).
Once we're able to reproduce the problem we can get straight to finding a solution for you!