Roof Rack on 5 door

Hi,

I have been trying to fit my new roof rack (Atera Signo) to my Megane II.

I had to drill out the plastic lugs in the roof under the plastic flaps as they wouldn't come out, but trying to screw in the screws for the roof rack and on all bar one of the locating bolts are extremely tight.

Would using some WD40 or some other grease help in locating the screws or are they just very tight as they've never been used before ? I don't want to shear the screws in the bolts so I have left the rack off for now.

Any hlep greatly appreciated.

Thanks