Target disk mode not working

I have a Macbook Pro (Retina 15" mid 2015) running OS X 10.11.6. I am trying to connect a MacBook (13" mid 2009) in target disk mode to the Macbook Pro. The Macbook's startup disk is full and it will not boot except in Recovery mode or target disk mode. There is apparently a misbehaving app that is gobbling up disk I want to access the Macbook's disk in target mode to delete some files and make room. I have the Macbook connected to the Macbook Pro using a Belkin Firewire 2M cable 9 pin/6pin-ZML connected to an Apple Thunderbolt - Firewire Adapter. Macbook boots into target disk mode, showing the Firewire logo on the Macbook screen. Macbook Pro doesn't recognize this target disk in Finder. Disk Utility on MacBook Pro recognizes the target disk as APPLE Target Media, with a MacIntosh HD partition. Highlife the APPL Firewire Target Media and it shows:

o Macintosh HD

159.83 GB

Location: External | Capacity 160.04 GB

Connection: Firewire | Child Count: 3

Partition Map: GUID partition | Type: Disk

S.M.A.R.T. status - Not supported | Device: Disk 3

Highlight Macintosh HD and it shows:

Macintosh HD

159.18 GB Firewire External Physical Volume OS X Extended

Mount Point: Not Mounted | Type: Firewire External Physical Volume

Capacity: 159.18 GB | Available: Zero KB

Used: 159.18 GB | Owners: Disabled

Device: disk2s2 | Connection: Firewire

NOTE: When I tried to Mount Macintosh HD, The External APPL Firewire Target Disk got listed multiple times (last count 10), with the only differences being Device: disk3s2, disk4s2.....disk10s2

Any suggestions???