Are you sure that function exists in the database?

>
>I created a Scalar-Valued Function (e.g. named 'MyFunction'). Then I try to execute it from SSMS as
>

>use [MyDatabase]
>declare @teststring char(10) = ''
>set @teststring = 'fadasfasf'
>select dbo.MyFunction( @teststring )
>

>
>The problem is that the last line (select dbo.MyFunction .. has a squiggly red under line with message 'Cannot find either column dbo or the user-define function or aggregate "dbo.MyFunction" or the name is ambiguous.
>
>What am I missing?