Thank you , I have changed it to this
=DLookUp(" [CALENDAR]![FIN_MONTH] ","[CALENDAR]","[CALENDAR]![FIN_START] <= " & [Forms]![frmFinanceCheckTimesheet]![TIME_DATE] & " AND [CALENDAR]![FIN_YEAR] = " & DatePart("yyyy",[Forms]![frmFinanceCheckTimesheet]![TIME_DATE]))
but it does not return any...