Parameter and string data type

I have successfully passed integer and date parameters to an
Access parameter query, but not string data. The code is as
follows: (Thanks for your help in advance)

Private Sub Form_Load()
Dim cnn1 As ADODB.Connection
Dim cmdByRoyalty As ADODB.Command
Dim prmByRoyalty As ADODB.Parameter
Dim rstByRoyalty As ADODB.Recordset
Dim rstAuthors As ADODB.Recordset
Dim intRoyalty As String
Dim strAuthorID As String
Dim strCnn As String

' Open connection.
Set cnn1 = New ADODB.Connection
strCnn = "DSN=Test"
cnn1.Open
cnn1.CursorLocation = adUseClient

' Open command object with one parameter.
Set cmdByRoyalty = New ADODB.Command
cmdByRoyalty.CommandText = "test"
cmdByRoyalty.CommandType = adCmdStoredProc

' Get parameter value and append parameter.
intRoyalty = "Bench"
Set prmByRoyalty = cmdByRoyalty.CreateParameter("percentage" _
, adChar, adParamInput)
cmdByRoyalty.Parameters.Append prmByRoyalty
prmByRoyalty.Value = intRoyalty

' Create recordset by executing the command.
Set cmdByRoyalty.ActiveConnection = cnn1
Set rstByRoyalty = cmdByRoyalty.Execute
rstByRoyalty.Close
cnn1.Close

End Sub