Check_Item Is Always Equal To 0 When 2^32

Hello FR Gurus Any idea ? If I put a value lesser than 2^32. i.e. 4294967290 for “ ChilliSpot-Max-Total-Octets” in radgroupcheck, value can be read by FreeRadius and check_item has the correct value (4294967290). If I put value bigger than 2^32, (8589934592) check_item is always equal to 0. Thanks / Regards RM--