My pendrive mounts once and then not again, below is tail -f messages output

Jul 6 17:30:19 vector kernel: usb 1-6.4: new high speed USB device using ehci_hcd and address 12
Jul 6 17:30:19 vector kernel: usb 1-6.4: configuration #1 chosen from 1 choice
Jul 6 17:30:19 vector kernel: scsi11 : SCSI emulation for USB Mass Storage devices
Jul 6 17:30:24 vector kernel: Vendor: Memorex Model: Mini TravelDrive Rev: 6.16Jul 6 17:30:19 vector kernel: usb 1-6.4: new high speed USB device using ehci_hcd and address 12
Jul 6 17:30:19 vector kernel: usb 1-6.4: configuration #1 chosen from 1 choice
Jul 6 17:30:19 vector kernel: scsi11 : SCSI emulation for USB Mass Storage devices
Jul 6 17:30:24 vector kernel: Vendor: Memorex Model: Mini TravelDrive Rev: 6.16
Jul 6 17:30:24 vector kernel: Type: Direct-Access ANSI SCSI revision: 00
Jul 6 17:30:24 vector kernel: sd 11:0:0:0: Attached scsi removable disk sda
Jul 6 17:30:24 vector kernel: sd 11:0:0:0: Attached scsi generic sg0 type 0
Jul 6 17:30:25 vector vl-hot_mount: Starting vl-hot_mount...
Jul 6 17:30:25 vector vl-hot_mount: devname: sda
Jul 6 17:30:25 vector vl-hot_mount: volname: vol
Jul 6 17:30:25 vector vl-hot_mount: Mounting /dev/vl-hot/sda on /mnt/vl-hot/sda/vol
Jul 6 17:30:25 vector vl-hot_mount: /dev/vl-hot/sda not mountable...
Jul 6 17:30:25 vector vl-hot_mount: Finishing vl-hot_mount...

Jul 6 17:30:24 vector kernel: Type: Direct-Access ANSI SCSI revision: 00
Jul 6 17:30:24 vector kernel: sd 11:0:0:0: Attached scsi removable disk sda
Jul 6 17:30:24 vector kernel: sd 11:0:0:0: Attached scsi generic sg0 type 0
Jul 6 17:30:25 vector vl-hot_mount: Starting vl-hot_mount...
Jul 6 17:30:25 vector vl-hot_mount: devname: sda
Jul 6 17:30:25 vector vl-hot_mount: volname: vol
Jul 6 17:30:25 vector vl-hot_mount: Mounting /dev/vl-hot/sda on /mnt/vl-hot/sda/vol
Jul 6 17:30:25 vector vl-hot_mount: /dev/vl-hot/sda not mountable...
Jul 6 17:30:25 vector vl-hot_mount: Finishing vl-hot_mount...

Any idea what I need to do?