Knife Tool can't connect certain vertices

hey,

another problem with the knife tool.
i am not able to make a cut between those 2 vertices.
if i use connect everything works fine.
has anyone got a clue why the knife tool does not work properly?

cheers

No blend file ?

sorry, i’m not allowed to share the file unfortunately.
i was deleting the surrounding polygons to upload at least the fragement of the mesh but the error was gone once i did so :confused:

If you just want a new edge connecting those two vertices, select them and press j