Applying Grand Total on a single field in Report

Question

Hi,
M using visual studio 2010 and MS Access 2007. In my database, there are various fields which are either integer or long values but there is only one field 'Amount' on which i wana enable Grand Total in report wizard but when i select all the fields while designing a report it automatically consider integer or long values to sum it and showing  total of each field having integer datatype which i dont want. There's another problem, especially in vs 2010, there r three boxes in report wizard row group, column group and values. m puting all my fields in Values box cz i dont wana sort it by any group but in that case, it doesnt enable subtotal, grand total option, and putting one field say Sno. in a row group doesnt show my desired layout of report plus doing subtotal of all integer fields which i dont want either. please guide what datatype should i set to those fields where total is not required.
Regards,