无法分配到“SP_STATUS”，因为它是“方法组”

Question

public partial class Login : Form
    {
        string _FG;
        clsUserDetailBAL obj = new clsUserDetailBAL();
        public Login()
        {
            InitializeComponent();
        }

        private void Clear()
        {
            txtusername.Text = "";
            txtpassword.Text = "";

            _FG = "INSERT";
        }
        private void Login_Load(object sender, EventArgs e)
        {
            Clear();
        }

         private void Save()
        {
            int i = 0;
            if (_FG == "INSERT")
            {
                obj.SP_STATUS = "INSERT";
            }

            obj.USER_NAME = Convert.ToString(txtusername.Text);
            obj.PASSWORD= Convert.ToString(txtpassword.Text);
            i = obj.DataOpration(obj);

            if (i < 1)
            {
                if (_FG == "INSERT")
                {
                    MessageBox.Show("Registeration Fail");
                }

                return;
            }
            else
            {
                if (_FG == "INSERT")
                {
                    MessageBox.Show("Registration Success");
                }

                Clear();
            }

        }


    USE [stud]
    GO

    SET ANSI_NULLS ON
    GO
    SET QUOTED_IDENTIFIER ON
    GO

    ALTER PROCEDURE [dbo].[SP_studinfo]

        @SP_STATUS varchar(199),
        @std_id numeric(18,0),
        @std_fname varchar(50),
        @std_lname varchar(50),
        @std_contno numeric(18,0),
        @std_gen varchar(50),
        @std_bdate datetime,
        @city_id numeric(18,0),
        @state_id numeric(18,0),
        @country_id numeric(18,0),
        @std_status varchar(50),
        @ct_name varchar(50),
        @s_name varchar(50),
        @c_name varchar(50)
    AS


    BEGIN
        IF @SP_STATUS='MAXNO'
        BEGIN

            SELECT ISNULL( max(std_id),0)+1 from student_records
        END

        ELSE IF @SP_STATUS='INSERT'
        BEGIN
            INSERT INTO student_records
            (
            std_id,
            std_fname,
            std_lname,
            std_contno,
            std_gen,
            std_bdate,
            city_id,
            state_id,
            country_id,
            std_status
            )
            values
            (
            @std_id,
            @std_fname,
            @std_lname,
            @std_contno,
            @std_gen,
            @std_bdate,
            @city_id,
            @state_id,
            @country_id,
            @std_status
            )
        END



        ELSE IF @SP_STATUS='UPDATE'
        BEGIN
            UPDATE student_records
            SET
                std_fname=@std_fname,
                std_lname=@std_lname,
                std_contno=@std_contno,
                std_gen=@std_gen,
                std_bdate=@std_bdate,
                city_id=@city_id,
                state_id=@state_id,
                country_id=@country_id  
            WHERE
             std_id=@std_id
        END

            ELSE IF @SP_STATUS='DELETE'
            BEGIN
                    UPDATE  student_records
                SET
                    std_status='Deactive'
                WHERE std_id = @std_id
            END 

            ELSE IF @SP_STATUS='FillGrid'
            BEGIN
                Select * from student_records
            END

            ELSE IF @SP_STATUS = 'EDITDATA' 
            BEGIN
                SELECT * FROM student_records
                WHERE std_id = @std_id
            END


        --BEGIN
        --  SELECT c.country_id , c.c_name, s.s_name, s.state_id, ct.ct_name, ct.city_id FROM country_list c, state_list s, city_list ct
        --END

        BEGIN
             IF @SP_STATUS='FillCombo'
            BEGIN
                SELECT country_id, c_name  FROM country_list
            END

             IF @SP_STATUS='FillCombo1'

            BEGIN
                SELECT state_id, s_name FROM state_list
            END

             IF @SP_STATUS='FillCombo2'
            BEGIN
                SELECT city_id, ct_name FROM city_list
            END
        END

    END