I've used the following split function:

CREATE FUNCTION dbo.Splitfn(@String varchar(8000), @Delimiter char(1))       
returns @temptable TABLE (items varchar(8000))       
 as       
begin       
declare @idx int       
declare @slice varchar(8000)       
  
select @idx = 1       
    if len(@String)<1 or @String is null  return       
  
while @idx!= 0       
begin       
    set @idx = charindex(@Delimiter,@String)       
    if @idx!=0       
        set @slice = left(@String,@idx - 1)       
    else       
        set @slice = @String       
      
    if(len(@slice)>0)  
        insert into @temptable(Items) values(@slice)       

    set @String = right(@String,len(@String) - @idx)       
    if len(@String) = 0 break       
end   
return      

end

and i used this function in a query and it was executed

ALTER PROCEDURE [dbo].[Employees_Delete] 
-- Add the parameters for the stored procedure here
@Id varchar(50)
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;

-- Insert statements for procedure here

 if exists( select Emp_Id from Employee where Emp_Id=dbo.Splitfn(@Id,','))
begin
    update Employee set Is_Deleted=1 where Emp_Id=dbo.Splitfn(@Id,',')
    select 'deleted' as message
end 
END

but when i excute my store procedure giving values say (1,2) i got the error

Cannot find either column "dbo" or the user-defined 
function or aggregate "dbo.Splitfn", or the name is ambiguous.

I've checked my tablevalued functions the function 'splitfn' was there but I don't know what is going wrong? Any suggestions..