problem with Npgsql UNICODE <-> Latin2

Hello

    In my ASP.NET application I have problem with execution of
INSERT COMMAND with czech diacritics.

cn = New
NpgsqlConnection("Port=5432;Database=lrr;Server=triss.cesta;")
Dim cmd1 As New NpgsqlCommand("set client_encoding TO unicode", cn)
Dim cmd2 as New NpgsqlCommand("INSERT INTO ....")
cmd1.ExecuteNonQuery()  'ok
cmd2.ExecuteNonQuery()  'for ever / PROBLEM, ended on timeout.

If I don't set client_encoding, then insert work, but then I can't use
czech diacritics.

I have npgsql-0.6rc3 on Microsoft .NET

Can You help me
Thank You
Pavel Stehule