Jeff,

>I think I've successfully built the Jump Start for Windows Forms Application in C# (everything except this error handling works).
>
>In the final step (Testing the Customer Orders Form - C#) when I clear out the Customer ID field and press the save button I get the following:
>
>Object reference not set to an instance of an object.
> at OakLeaf.MM.Main.Windows.Forms.mmBusinessForm.SetErrorProvider(mmErrorProviderArgs arg)
> at OakLeaf.MM.Main.Windows.Forms.mmBusinessForm.DisplayErrorProviderRules(mmBusinessRuleBase bizRule)
> at OakLeaf.MM.Main.Windows.Forms.mmBusinessForm.DisplayBrokenRules(mmBusinessRule bizRule)
> at OakLeaf.MM.Main.Windows.Forms.mmBusinessForm.PostSaveProcessing(mmBusinessObject bizObj, String tableName, mmSaveDataResult result)
> at OakLeaf.MM.Main.Windows.Forms.mmBusinessForm.Save(mmBusinessObject bizObj, String tableName)
> at OakLeaf.MM.Main.Windows.Forms.mmButtonHelper.SaveHandler(Object button, String bindingSource, String bindingSourceMember, mmBaseBusinessObject& bizObj)
> at OakLeaf.MM.Main.Windows.Forms.mmButtonSave.mmButtonSave_Click(Object sender, EventArgs e)

Looks like you're getting an error when trying to display a broken rule. I recommend setting a breakpoint in mmBusinessForm.SetErrorProvider() to see what is causing the error. Do you know which rule is being broken and why?

Best Regards,