new genuine gearbox seal still leaking

[turbo diesel]

over the weekend i replaced my passenger side gearbox/driveshaft seal using a genuine vauxhall seal, i have the car 70 miles, had a look today and its leaking again in the same place
any ideas why this would happen

[plasma]

surface imperfection where it fits into the hole?

[turbo diesel]

inside the box or external i gave it a good clean externally and internally before inserting the seal

[justin32]

did you push it in enough? did you damage the surface getting the old one out?

I had to change one of mine last year and it was a ****** to get out and had to go careful otherwise i would of damaged the surface.

[turbo diesel]

everything was cleaned spotless and seal went in well flush with the box
whats the chances the diff bearings have play and diff moving up and down causing the leak