Target Display Mode

Hi I have an iMac mid 2011 21.5" and a macbook pro 2020. I am trying to use my iMac as a second display using command+f2 for target display mode, but it just makes an error sound. I have a thunderbolt 2 cable and an adapter for thunderbolt 3 to thunderbolt 2. I don't have an original keyboard, but i have modified the keys, so I can confirm the command button works.

• My iMac is OS 10.11.6 and MacbookPro is 10.15.6
• I have tried resetting pram
• I have done a hardware test and have no problems
• I have unplugged everything and plugged back in after a few mins
• I do not have the checkbox on keyboard preferences for "Use all F1, F2, etc. keys as standard functions keys" so I don't need to click fn
• I have tried installing virtual kvm but it says Ready to accept connections.
• I have tried installing typeeto and using my macbook pro as a bluetooth keyboard to run command+f2 but get same error sound.
• Both macs are up to date.
• Yes I am logged in to both devices and they are both plugged in.
• On System information, on thunderbolt it says no devices connected:

Thunderbolt Bus:

Vendor Name: Apple Inc.

Device Name: iMac

UID: 0x0001000A1BA67DC0

Route String: 0

Firmware Version: 25.1

Domain UUID: 67E2BD46-7F5A-2E55-9ED5-D191FD5B79DB

Port:

Status: No device connected

Link Status: 0x7

Speed: Up to 10 Gb/s x2

Receptacle: 1

Port Micro Firmware Version: 2.1.3

• I have tried connecting the iMac to my macbook air using the regular thunderbolt 2 cable, but still same issue.

I really don't know what else to try. I have also spoken to apple support on the chat service, but I had already done everything they had suggested.