I want to create a simple SQL table in Visual Studio 2012 that th id field is Auto increment primary key, so I do like this :

But when I want to Update and create table it errors :
** Highlights
Tables that will be rebuilt
None
Clustered indexes that will be dropped
None
Clustered indexes that will be created
None
Possible data issues
None
** User actions
Create
[dbo].[sotbl] (Table)
Default Constraint on [dbo].[sotbl].[Id] (Default Constraint)
** Supporting actions

Creating [dbo].[sotbl]... Creating Default Constraint on [dbo].[sotbl].... (86,1): SQL72014: .Net SqlClient Data Provider: Msg 1754, Level 16, State 0, Line 1 Defaults cannot be created on columns with an IDENTITY attribute. Table 'sotbl', column 'Id'. (86,1): SQL72014: .Net SqlClient Data Provider: Msg 1750, Level 16, State 0, Line 1 Could not create constraint. See previous errors. An error occurred while the batch was being executed.