An error occurred while refreshing the data from field 'Services.unitset_id' to property 'SelectedValue' on control 'editUnitSet.'

When I open the page from menu. I have seen the added record.

I've tested my screen and I had no error for the above condition. It might be under specific conditions. If I find that case, I 'll inform you.  

In my form ; There is a grid which lists the objects (called Services).

and There are UI controls which shows the current object's properties. (Current object is selected on the grid.)

If Business Object has no records. (After a query) I've got the error below ;

"An error occurred while refreshing the data from field 'Services.unitset_id' to property 'SelectedValue' on control 'editUnitSet.'"

editUnitSet is a combobox and populated on formload from another Business Object. Since Business Object (Services Object) has no current record, and has no valid unitset_id as well. Binding mechanism goes on working.

I've searched from help and found the topic ;

What Happens to an Empty Business Object
StrataFrame automatically removes all control bindings when the business object has no records. 
The instant the business object is populated with data, the bindings are automatically re-created and the presentation layer controls are updated.

If so, why do I get the error ? What is wrong with my case ?

I 've requeried the object (which is bound to the grid and UI controls which show current object) with parameters that returns records . Object had records after query. I've got the new error. (See details)

Type : System.InvalidCastException, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
Message : Specified cast is not valid.
Source : Medin.Business.Materials.New
HelpLink :
TargetSite : Void SetValue(System.Object, System.Object)
StackTrace :
 Medin.Business.Materials.Purchase.Services.Field_unitset_id_Descriptor.SetValue(Object component, Object Value)
  C:\Documents and Settings\ertan.deniz.KULLANICI\My Documents\Visual Studio 2005\Projects\Medin.Materials\Medin.Materials.Purchase.Business\Purchase\Objects\Services.Designer.cs:line 1235
 System.Windows.Forms.BindToObject.SetValue(Object value)
 System.Windows.Forms.Binding.PullData(Boolean reformat, Boolean force)
 System.Windows.Forms.Binding.UpdateIsBinding()
 System.Windows.Forms.Binding.CheckBinding()
 System.Windows.Forms.Binding.SetListManager(BindingManagerBase bindingManagerBase)
 System.Windows.Forms.ListManagerBindingsCollection.AddCore(Binding dataBinding)
 System.Windows.Forms.BindingsCollection.Add(Binding binding)
 System.Windows.Forms.BindingContext.UpdateBinding(BindingContext newBindingContext, Binding binding)
 System.Windows.Forms.Binding.SetBindableComponent(IBindableComponent value)
 System.Windows.Forms.ControlBindingsCollection.AddCore(Binding dataBinding)
 System.Windows.Forms.ControlBindingsCollection.Add(Binding binding)
 MicroFour.StrataFrame.Business.BusinessLayer.AddBinding(Control ControlToRefresh, String PropertyName, String FieldName)
 MicroFour.StrataFrame.Business.BusinessLayer.RefreshControl(IBusinessBindable ControlToRefresh, Boolean DataPresent)

Is the order of assignment true ? I expect that right side must be left side ? Because, I'm displaying values from DB.

Do you explain the process briefly ? Fill, Bind etc.

private class Field_unitset_id_Descriptor : MicroFour.StrataFrame.Business.FieldPropertyDescriptor
        {
            public Field_unitset_id_Descriptor() : base("unitset_id") { }
            private System.Type _PropertyType = typeof(System.Int32);
            public override object GetValue(Object component)
            {
                return ((Services)component).unitset_id;
            }
            public override void SetValue(Object component, object Value)
            {
                ((Services)component).unitset_id = (Nullable<System.Int32>Value; (Error : Specified Cast is not valid.)
            }
            public override System.Type PropertyType
            {
                get
                {
                    return this._PropertyType;
                }
            }
            public override System.Type ComponentType
            {
                get
                {
                    return _ComponentType;
                }
            }
        }

But, Requery object and no records. This is also working.

Requery object but there are records at this time. I 've got the error.

So at present, this is on a list to look at, and it is something that we will try to look at prior to the final 1.6.6 build.  If you want to provide a sample showing the error versus just showing a code snippet, it will definitely speed up the process.

The line from my code shows that unitset_id gets value.

((Services)component).unitset_id = (Nullable<System.Int32>Value; (Error : Specified Cast is not valid.)

But message says  control gets value ;

"An error occurred while refreshing the data from field 'Services.unitset_id' to property 'SelectedValue' on control 'editUnitSet.'"

I don't see anything past an invalid cast exception.  Why can't you just return an alternate value on Null so that a valid value is returned to the grid?  I do not believe this to be a BBS or BO "bug" or "issue" but rather how it is designed.  If the control to which you are binding doesn't support a null value being returned, then you would want to ensure that it can be cast by supplying a valid value.  Just from looking at your code snippet and stack trace, this is what I would recommend.

Original point in my project also have been tested and also no problem.

The problem may be related development environment (DLL versions etc).