How to detect current culture in a web service ASP.Net

While refering to the article

http://www.aspsnippets.com/Articles/Implement-jQuery-Autocomplete-using-Web-Service-in-ASP.Net.aspx

I need to select a proper SQL procedure based on a current culture selected by a user and I need to select it inside the web service.

Example:

Using cmd As New SqlCommand()
                cmd.CommandText = "dbo.Search_ItemsInFullText_" & Thread.CurrentThread.CurrentCulture.TwoLetterISOLanguageName
                cmd.CommandType = Data.CommandType.StoredProcedure
                cmd.Parameters.AddWithValue("@SearchText", prefix)
                cmd.Connection = conn
                conn.Open()

but this does not work.

How can I detect a current culture in a web service? Thanks.