[Petronski]

"Did not" was perfectly valid...

"Did not" implies they do not exist. "Have not" is more accurate because it states only that they have not been located.

[AndrewC]

"Did not" implies they do not exist.

You are out of your mind. If I did not find the matching sock to a sock, it does not imply that it does not exist. It only implies that I did not find it.

[Ichneumon]

Please do not feed the color-fonted troll.