Error in Function

Question

CREATE FUNCTION [usermanagement].[MD5Encript](@str [nvarchar](200))

RETURNS [nvarchar](200) WITH EXECUTE AS CALLER

AS

EXTERNAL NAME [MD5Encryption].[UserDefinedFunctions].[MD5Encript]

GO

 

It gives error  like

 

Msg 6528, Level 16, State 1, Procedure MD5Encript, Line 1 [Batch Start Line 2]

Assembly 'MD5Encryption' was not found in the SQL catalog of database 'SB'.

 

 

 

 Please help