I think I'm missing something...

I have a MVC app which is basically a form with an embedded grid control.

The View has a Model which is an object with a bunch of properties including a IQueryable Items list

I bind the DataSource property of the grid to Model.Items and everything displays just fine

However, when I submit the form back to the controller for processing the Items property of my object is always null?

What am I doing wrong, I have AutoCommit=true, I would have expected that to update the Items collection locally then on submitt the data would be returned

                        <!-- Items -->
                        @( Html.Infragistics().Grid<Purchasing.Models.PurchaseOrderItem>()
                               .AutoGenerateColumns(false)
                               .AutoCommit(true)
                               .ID("PurchaseOrder_Grid")
                               .Columns(column =>
                               {
                                   column.For(x => x.jobId).DataType("string").HeaderText("Job").Width("100");
                                   column.For(x => x.quantity).DataType("number").HeaderText("Quantity").Width("100");
                                   column.For(x => x.uom).DataType("string").HeaderText("Units").Width("100");
                                   column.For(x => x.item).DataType("string").HeaderText("Item").Width("300*");
                                   column.For(x => x.glAcct).DataType("string").HeaderText("GL Account").Width("300");
                                   column.For(x => x.id).Hidden(true);
                               })
                               .Features(features =>
                               {
                                   features.Updating().EnableAddRow(true);
                                   features.Updating().EnableDeleteRow(true);
                                   features.Updating().ColumnSettings(settings =>
                                   {
                                       settings.ColumnSetting().ColumnKey("quantity").ReadOnly(false).EditorType(ColumnEditorType.Numeric).Required(true);
                                       settings.ColumnSetting().ColumnKey("item").ReadOnly(false).Required(true);
                                       settings.ColumnSetting().ColumnKey("jobId").ReadOnly(false).EditorType(ColumnEditorType.Text);
                                       settings.ColumnSetting().ColumnKey("glAcct").ReadOnly(false);
                                   });
                               })
                               .DataSource(Model.Items)
                               .PrimaryKey("id")
                               .ClientDataSourceType(ClientDataSourceType.JSON)
                               .Width("100%")
                               .Height("150px")
                               .DataBind()
                               .Render()
                              )