Dear Abdul Aleem. i find your error and please try this code.
create PROCEDURE [dbo].[usp_Update_Service_Program_Detail]
@PK_Service_Program_County_RateCap_Detail int,
@Unit_Type int,
@Rate_Cap decimal(15,2),
----@County int,
@ModifiedBy nvarchar(50),
@ModifiedOn datetime=getdate
AS
BEGIN
select '220' 'Col' -- Test statement
--Logic is here
END
exec usp_Update_Service_Program_Detail @PK_Service_Program_County_RateCap_Detail= 53196434, @Unit_Type=1
, @Rate_Cap=100
, @ModifiedBy='aaleemmo'
, @ModifiedOn=''