Problem with image data type in ms sql server and .net ibatis

[Heath, Terry]

Hi -

I get this error:
UnitTesting.DataLayerTests.PAF_ATTACHMENTS_Create :
System.Data.SqlClient.SqlException : Operand type clash: nvarchar is
incompatible with image

When trying to insert a row into the database. I've got a column with
data type = image, and a property (tied to the column in the datamap)
with type byte[]. 

I don't know what I should set as the nullValue for the byte[] property.
Here's the paramater map and the insert statement:

<parameterMaps>
 
        <parameterMap id="InsertPAF_ATTACHMENTSParam"
class="PAF_ATTACHMENTS">
            <parameter property="TransNo" nullValue="-9999" />
            <parameter property="ImageData" />
            <parameter property="ContextType" />
            <parameter property="FileName" />
            <parameter property="UserID" />
            <parameter property="FileSize" nullValue="-9999" />
            <parameter property="Timestamp" nullValue="1/1/0001 12:00:00
AM" />
        </parameterMap>
 
        <parameterMap id="UpdatePAF_ATTACHMENTSParam"
extends="InsertPAF_ATTACHMENTSParam">
            <parameter property="AttachmentID" nullValue="-9999" />
        </parameterMap>
 
    </parameterMaps>

<insert id="PAF_ATTACHMENTSCreate"
parameterMap="InsertPAF_ATTACHMENTSParam">
            <selectKey property="AttachmentID" resultClass="Integer">
                select cast(@@IDENTITY as int) as value
            </selectKey>
            insert into [PAF_ATTACHMENTS] (
                TransNo, 
                ImageData, 
                ContextType, 
                FileName, 
                FileSize,
                UserID, 
                Timestamp
            ) values (
                ?, 
                ?, 
                ?, 
                ?, 
                ?, 
                ?,
                ?
)        </insert>

Here's the relevant parts of the code:
Private _imageData() As Byte
...
        Public Property ImageData() As Byte()
                Get
                        Return Me._imageData
                End Get
                Set(ByVal Value As Byte())
                        Me._imageData = Value
                End Set
        End Property


If you know what I'm doing wrong, please help :)

Thanks!
Terry