函式 'Instance' 未回有所有程式路的值。使用果，可能在行段生 null 考例外。

VB.NET code

 Private frm1 As Form_customer_order    Public Function Instance(ByVal frm As Form_customer_order)        frm1 = frm    End Function

[解决办法]
Private frm1 As Form_customer_order=Nothing



Public Function Instance(ByVal frm As Form_customer_order)

frm1 = frm

End Function