Take a close look at this picture and you can see that the seal does not look quite right. The lip is above the top surface of the roof. Since it is possible to install the front seal upside down and many of the sunroofs from 1965 to 1985 be careful that you get it right. The top of the seal, when installed in the groove, should be flush with the top of the car roof.
It could be that you installed in upside down
W110 W111 W112 Sedan
W111 W112 Coupe