SQL Server :: Stored Procedure Not Working Properly

ALTER Proc [dbo].[Usp_CheckUserLogin]
(
@Username varchar(20),
@Password varchar(20)
)
as
begin
Declare @RowCount int
Declare @RowCount1 int
set @RowCount = (select distinct UsrId from UserMast where username=@username COLLATE SQL_Latin1_General_Cp1_CS_AS )
set @RowCount1=(select distinct UsrId from UserMast where [password]=@password COLLATE SQL_Latin1_General_Cp1_CS_AS)
if(@RowCount > '0' and @RowCount1 > '0')
if (@RowCount=@RowCount1)
begin
-- select U.UsrId,U.FirstName,U.LastName,U.Email,U.companyId,U.role,R.RoleName from UserMast U join rolemast R on U.Role=R.RoleId
-- where usrid=@RowCount
select 'success'
end
if(@RowCount > '0' and @RowCount1 = '0')
begin
select 'username exist'
end
if(@RowCount= '0' and @RowCount1 > '0')
begin
select 'password exist'
end
if(@RowCount= '0' and @RowCount1 = '0')
begin
select 'both not exist'
end
--return @RowCount1
end

my procedure not give me result i think my syntax is not correct