Cannot Activate Acrobat XI On New Computer Although Deactivated On Old Computer

I have a legitimate standalone perpetual licence for Acrobat XI Pro (Windows), currently updated to 11.0.23.

Before disposing of my previous PC, I specifically used Help → Deactivate while the computer was online. Acrobat reported that the deactivation had completed successfully. I therefore no longer have access to that computer.

I have now installed Acrobat XI Pro on its replacement. My serial number is accepted as valid, but activation fails with:

“The serial number is already in use by the maximum allowed computers.”

Selecting “Retry activation. I have already deactivated one of my other computers” simply returns the same result.

I understand that Acrobat XI is end-of-life and that Adobe no longer provides normal technical support for it. I am not asking for technical support for Acrobat XI.

The issue I am reporting is specifically that Adobe's licensing system appears not to have recorded a deactivation which Acrobat explicitly reported to me as successful. I relied on that successful-deactivation confirmation before disposing of the old computer, so I now have no means of repeating the operation.

Could an Adobe Community Manager please inspect the server-side registration and activation/deactivation history for my serial number, as Adobe Community Managers have been able to do for other Acrobat XI users, and confirm:

1. Whether Adobe's servers recorded the successful deactivation from my previous computer; and

2. How many activations Adobe's database currently records against the serial number.

I still have the original serial number and can provide it privately to an authorised Adobe employee if required. I will not post the serial number publicly.

I also have a current Adobe subscription under my Adobe account, although Acrobat XI itself was purchased separately as a standalone perpetual product.

Thank you.