833 Leaking Again

I replace the rear seal on my 833, and it is leaking again, without moving the car. Could I have over filled it?

H4
C 99129
H29P9F164315
PP 833 2900 0140
C9912816-2
Left hand side of transmission
C95664-Z (8X13)

Rear seal: TS85-63B Tailshaft Seal, 30 spline.

Thanks
Bear