Enabling DMA Mode On IDE Drive

I cannot enable DMA mode on /dev/hda when attemping to enable it via ssh

Code:
hdparm -d1 /dev/hda
/dev/hda:
setting using_dma to 1 (on)
HDIO_SET_DMA failed: Operation not permitted
using_dma = 0 (off)

Code:
hdparm -tT /dev/hda
/dev/hda:
Timing cached reads: 1632 MB in 2.00 seconds = 814.90 MB/sec
Timing buffered disk reads: 8 MB in 3.42 seconds = 2.34 MB/sec
I am running CentOS 4.7 and cPanel 11. cPanel also shows DMA is not enable on this drive. Kernel: 2.6.9-78.0.13.ELsmp

Code:
cat /boot/config-2.6.9-78.0.13.ELsmp |grep DMA
CONFIG_GENERIC_ISA_DMA=y
CONFIG_BLK_DEV_IDEDMA_PCI=y
# CONFIG_BLK_DEV_IDEDMA_FORCED is not set
CONFIG_IDEDMA_PCI_AUTO=y
# CONFIG_IDEDMA_ONLYDISK is not set
# CONFIG_HPT34X_AUTODMA is not set
CONFIG_BLK_DEV_IDEDMA=y
# CONFIG_IDEDMA_IVB is not set
CONFIG_IDEDMA_AUTO=y
CONFIG_SCSI_SYM53C8XX_DMA_ADDRESSING_MODE=1
CONFIG_PDC_ADMA=m

Code:
hdparm -i /dev/hda
/dev/hda:
Model=WDC WD2500JB-00REA0, FwRev=20.00K20, SerialNo=WD-WMAN542173
Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq }
RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=50
BuffType=unknown, BuffSize=8192kB, MaxMultSect=16, MultSect=16
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=268435455
IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes: pio0 pio3 pio4
DMA modes: mdma0 mdma1 mdma2
UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5
AdvancedPM=no WriteCache=enabled
Drive conforms to: device does not report version:
* signifies the current active mode