BLOB fields trouble

[HABJAN ®iga]

I'am trying to insert a record with a blob field in it:
create table KC113DELO.Test1(
ID INT NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1,
NO CACHE ),
TTEST VARCHAR(30),
TBLOB BLOB(50000) NOT LOGGED NOT COMPACT
) DATA CAPTURE NONE IN USERSPACE1
vb.net code:
Dim datB As New ADODB.Connection
datB.Open(" DSN=Kc113db2", "db2admin", "db2admin")

Dim recA As New ADODB.Recordset
recA.Open(" select id,tTest,tblob from kc113delo.test1", datB,
ADODB.CursorTypeEnum.adOpenKeyset, ADODB.LockTypeEnum.adLockPessimistic)
With recA
.AddNew()
.Fields("tTest").Value = "asd" & Date.Now.Today
.Fields("tBlob").AppendChunk("this is a test")
.Update()
End With
I get (on update):
An unhandled exception of type 'System.Runtime.InteropServices.COMException'
occurred in TestChunk.exe
Additional information: [IBM][CLI Driver] CLI0102E Invalid conversion.
SQLSTATE=07006

I tryed insering byte array, string: same error

--- using vb.net on framework 1.1, IBM DB2 7.2, ODBC connection

thanks for any advice
best re,
habix