The installer is probably seeing an existing partition table and partition of a type that it doesn't understand.

Since you say the disk is empty, I'd first try using the partitioning tool to create entirely new partition(s). If this is to be an OS X-only system, or if you plan to dual boot with Linux, make them GUID Partition Table (GPT) partitions. (This option is hidden away on a sub-menu; you've got to click "Advanced" or "Options" or some such to get to it -- I don't recall the exact wording.) If you plan to dual-boot with Windows, make them Master Boot Record (MBR) partitions.

If this doesn't work, try using Parted Magic to create the partitions. This is a Linux-based emergency boot CD-R with various partitioning tools. I'm pretty sure it includes the ability to make HFS+ ("Mac OS Extended") partitions, although you may need to enable journaling after installing OS X. You'll need to use both a partitioning tool (fdisk or GNU Parted for MBR, gdisk or GNU Parted for GPT) and a filesystem-creation tool (mkfs.hfsplus). When you create a partition, make it of type 0xAF for MBR in fdisk or AF00 for GPT in gdisk. I'm not sure about GNU Parted offhand; I don't recall if it supports HFS+. If it does, you'd probably tell it to create a partition of type hfsplus, hfs, or mac. In any event, if you go this route, the partition should be detected by the installer when you reboot.

[EDIT] hi, im sory I forgot to write that i did this before! I even tried to make partition but still it sais failed! and tht is the reason i erased everything with Parted Magic and made the entire drive to hfs+, same error occured and hence i changed the whole drive to ntfs! its still the same i dont know wht to do!