SQL Server Error: Split is not a recognized built-in function name

Hi,

I create one function for split string in sql server 2008

when i call that funtion from select query it will display the following error

'Split' is not a recognized built-in function name.

I am tring with schema name it will also display error

annot find either column "dbo" or the user-defined function or aggregate "dbo.Split", or the name is ambiguous.

How to fix this