Create Table Error

While Creating the Table in SqlServer200 It is givin the Error like

Server: Msg 2749, Level 16, State 2, Line 1
Identity column 'CustID' must be of data type int, bigint, smallint,
tinyint, or decimal or numeric with a scale of 0, and constrained to
be nonnullable.

Can't we create a Identity for character Field?
my Code is follows

CREATE TABLE Rtest (CustID Varchar(10) NOT NULL IDENTITY,
CustName VARCHAR(40) NOT NULL)NO, You cant have an varchar or char field as an identity column

Identity column must be of type numeric ,or the types specified in the error u have given.|||Identity property is to ensure the column value to increase by the defined step. How would a varchar increase?