Time Machine error: backup volume could not be found

please help me !
Time Machine doesn´t work.
backup volumen is formated and choosen correctly, but when backup should start, i just get the error "backup volume could not be found"

i´ve already tested serveral fixes, unfortunately without success.

my system:
intel q6600
asus p5k-e wifi ap
kalyways 10.5.4 (10.5.2+updates)
pny 8800 gts 512 (g92)
4 gb ddr 3 ram (800mhz)

First: Grab one entire HDD, format it using Disk Utility in HFS+ format.

If you using same HDD for OSX maybe had some problems.

Goodluck,