System.IndexOutOfRangeException when using composite key

[Richard Bláha]

Hi, I'm trying to map master / detail result maps using composite key and I'm 
getting:

System.IndexOutOfRangeException: FIELD_ID

Here is a example.

<resultMap id="ReportDetail-ExportResultMap" class="ReportDetail">
...
    <result property="Subreports" column="{ReportId=REPORT_ID, 
FieldId=FIELD_ID}" select="Report-GetByParent" />
</resultMap>

<select id="Report-GetByParent" resultMap="Report-DefaultResultMap">
...
            WHERE
                PARENT_REPORTID = #ReportId# AND
                PARENT_FIELDID = #FieldId#
</select>

Can anyone advice?
Thanx

-rb-