[Solved] ASP.Net Calling Stored Procedure Error: Must declare the scalar variable @From

I unable to create procedure , i have getting mention error.

Msg 156, Level 15, State 1, Procedure spx_GetEmployees, Line 3 Incorrect syntax near the keyword 'NULL'. Msg 137, Level 15, State 2, Procedure spx_GetEmployees, Line 12 Must declare the scalar variable "@From". Msg 137, Level 15, State 2, Procedure spx_GetEmployees, Line 16 Must declare the scalar variable "@From". Msg 137, Level 15, State 2, Procedure spx_GetEmployees, Line 20 Must declare the scalar variable "@From

CREATE PROCEDURE spx_GetEmployees
    @Filter VARCHAR(50),
    @From DATETIME NULL,
    @To DATETIME NULL
AS
BEGIN
    SET NOCOUNT ON;
       
    IF @Filter = 'ALL'
        SELECT EmployeeID, FirstName + ' ' + LastName 'Name', City, Country
        FROM Employees
        WHERE (BirthDate BETWEEN @From AND @To) OR (@From IS NULL OR @To IS NULL)
    ELSE IF @Filter = '5'
        SELECT TOP 5 EmployeeID, FirstName + ' ' + LastName 'Name', City, Country
        FROM Employees
        WHERE (BirthDate BETWEEN @From AND @To) OR (@From IS NULL OR @To IS NULL)
    ELSE
        SELECT EmployeeID, FirstName + ' ' + LastName 'Name', City, Country
        FROM Employees
        WHERE Country=@Filter AND (BirthDate BETWEEN @From AND @To) OR (@From IS NULL OR @To IS NULL)
END
GO
==========
CREATE TABLE "Employees" (
    "EmployeeID" "int" IDENTITY (1, 1) NOT NULL ,
    "LastName" nvarchar (20) NOT NULL ,
    "FirstName" nvarchar (10) NOT NULL ,
    "Title" nvarchar (30) NULL ,
    "TitleOfCourtesy" nvarchar (25) NULL ,
    "BirthDate" "datetime" NULL ,
    "HireDate" "datetime" NULL ,
    "Address" nvarchar (60) NULL ,
    "City" nvarchar (15) NULL ,
    "Region" nvarchar (15) NULL ,
    "PostalCode" nvarchar (10) NULL ,
    "Country" nvarchar (15) NULL ,
    "HomePhone" nvarchar (24) NULL ,
    "Extension" nvarchar (4) NULL ,
    "Photo" "image" NULL ,
    "Notes" "ntext" NULL ,
    "ReportsTo" "int" NULL ,
    "PhotoPath" nvarchar (255) NULL
)