There is a static property called LicenseKey on ShinobiDataGrids (NB plural!) that you can set prior to your objects constructor which should fix this problem.
It looks like the issue is because the DataGrid sets its own license key from this static property in its constructor. However, because the value is null by default it throws an ArgumentNullException in DataGrid subclasses due to slightly stricter checks in our bindings. I'll look into improving this in a future version.
Needless to say, this only affects the trial version of our product.
Thanks, and kind regards,