3.6 mm is the diameter of the outer jacket. The conductors inside that jacket, 6 of them, are insulated from each other. The diameter of the conductor including insulation must be about 0.9 mm. 1.1 mm is just too large to be pushed in enough to connect.
Cordially,
Charles W. Scouten, Ph.D.
Innovation Manager
Neuroscience Tools
630 964 0501