change -修复产品型号为空问题

ProductionSystem/Forms/HomeForm.cs

@@ -187,7 +187,10 @@ namespace ProductionSystem.Forms
             var selectedItem = cmbProductType.SelectedItem as ListItem;
             if (selectedItem == null || string.IsNullOrEmpty(selectedItem.Value))
             {
-                CustomMessageBoxHelper.AlertShow(this, "产品型号为空！");
+                if(selectedItem.Text != "--请选择--")
+                {
+                    CustomMessageBoxHelper.AlertShow(this, "产品型号为空！");
+                }               
                 return;
             }
             Program.ProductType = selectedItem.Value;//选中的产品型号