CREATE FUNCTION dbo.fnGetNoOfBusinessDays 
(@STARTDATE datetime,@EntDt datetime)
RETURNS TABLE 
AS
RETURN 
;with DateList as  
 (  
    select cast(@STARTDATE as datetime) DateValue  
    union all  
    select DateValue + 1 from    DateList     
    where  DateValue + 1 < convert(VARCHAR(15),@EntDt,101)  
 )select * from DateList where DATENAME(WEEKDAY, DateValue ) not IN ( 'Saturday','Sunday' )
GO

CREATE FUNCTION dbo.testFunction
(@STARTDATE datetime,@EntDt datetime)
RETURNS TABLE
AS
RETURN

with DateList as 
 ( 
    select cast(@STARTDATE as datetime) DateValue  
    union all 
    select DateValue + 1 from    DateList     
    where  DateValue + 1 < convert(VARCHAR(15),@EntDt,101) 
 )select * from DateList where DATENAME(WEEKDAY, DateValue ) not IN ( 'Saturday','Sunday' )
GO

CREATE FUNCTION dbo.testFunction
(@STARTDATE datetime,@EntDt datetime)
RETURNS TABLE
AS
RETURN
 
with DateList as
 (
    select cast(@STARTDATE as datetime) DateValue 
    union all
    select DateValue + 1 from    DateList    
    where  DateValue + 1 < convert(VARCHAR(15),@EntDt,101)
 )select * from DateList where DATENAME(WEEKDAY, DateValue ) not IN ( 'Saturday','Sunday' )
GO

select dbo.testFunction(getdate(),getdate()+30);

Msg 4121, Level 16, State 1, Line 1
Cannot find either column "dbo" or the user-defined function or aggregate "dbo.testFunction", or the name is ambiguous.

select * from dbo.testFunction(getdate(),getdate()+30);

--results:
2009-07-27 00:15:08.460
2009-07-28 00:15:08.460
2009-07-29 00:15:08.460
2009-07-30 00:15:08.460
2009-07-31 00:15:08.460
etc....