SQLAdd - i get bug - what to change

Sub SQLAdd()
Dim cnn As Connection
Dim cmn As Command
Set cmn = New Command
Set cnn = New Connection

strConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\prog\a.mdb"
cnn.Open strConnectionString
Set cmn.ActiveConnection = cnn

'Define SQL query.
cmn.CommandText = "INSERT INTO book (personName, phone) VALUES (?, ?)"

'Save a prepared (or pre-compiled) version of the query specified in CommandText
'property before a Command object's first execution.
cmn.Prepared = True

'Define query parameter configuration information.
cmn.Parameters.Append cmn.CreateParameter(personName, adVarChar, , 255)
cmn.Parameters.Append cmn.CreateParameter(phone, adVarChar, , 255)

'Define and execute first insert.
cmn("personName") = txtName.Text 'here is the bug
'
cmn("phone") = txtPhone.Text
cmn.Execute , , adCmdText + adExecuteNoRecords

cnn.Close
Set cnn = Nothing
Set cmn = Nothing
End Sub

so what should i write?