attempted to assign id from null one-to-one property: ContentItemRecord - Orchard CMS

[rox]

I'm writing the module for Orchard CMS.There are several tables. In Migrations.cs:It works fine:\[code\] SchemaBuilder.CreateTable("CustomerPartRecord", table => table .ContentPartRecord() .Column<string>("FirstName", c => c.WithLength(50)) .Column<string>("LastName", c => c.WithLength(50)) .Column<string>("Title", c => c.WithLength(10)) .Column<DateTime>("CreatedUtc") ); ContentDefinitionManager.AlterPartDefinition("CustomerPart", part => part .Attachable(false) ); ContentDefinitionManager.AlterTypeDefinition("Customer", type => type .WithPart("CustomerPart") .WithPart("UserPart") ); return 6;\[/code\]But it doesn't work:\[code\] SchemaBuilder.CreateTable("OrderPartRecord", t => t .ContentPartRecord() .Column<int>("CustomerId", c => c.NotNull()) .Column<DateTime>("CreatedAt", c => c.NotNull()) .Column<decimal>("SubTotal", c => c.NotNull()) .Column<string>("Status", c => c.WithLength(50).NotNull()) ); ContentDefinitionManager.AlterPartDefinition("OrderPart", part => part .Attachable(false) ); ContentDefinitionManager.AlterTypeDefinition("Order", type => type .WithPart("OrderPart") );\[/code\]There's error when I try to add Order. Error: attempted to assign id from null one-to-one property: ContentItemRecord What's wrong?