Backup Fails Using SMO With Big Databases

Hello
I'm seeing the backup using SMO fails with big databases (>15GB). I
have a 2GB database and I can see the command go thru. in Profiler but
after it's about 50-70% done, I get an exception saying backup failed.
There is no details on the SQLServer log.

Here's the code snippet:

bk.Initialize = m_backupInit;
bk.PercentCompleteNotification = 10;
bk.PercentComplete += new
PercentCompleteEventHandler(bk_PercentComplete);
bk.SqlBackup(m_Server);

Here's the command as captured by SQL-Profiler:
BACKUP DATABASE [Test_MODEL] TO DISK = N'D:Temp
Test_Model_Backup.dat' WITH NOFORMAT, INIT, NOSKIP, REWIND,
NOUNLOAD, STATS = 10

Has anyone else seen this. The wierd thing is it works using old SQL-
DMO.

thanks
Sunit