There are a couple of things to check out...first, was the seal distorted when it was put in? Was it put in the wrong way round? Was the axle shaft grooved or marked in any other way? (It should have a perfectly polished appearance for the lips of the seal to work). Finally, is the axle breather clear?
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.