Fender screws are generally smaller than aftermarket versions.
Slot head screws are also 5mm head diameter.
I would guess the pickguard is drilled and countersunk for the usual aftermarket philips head screws which are 6mm head diameter.
Genuine Fender pickguards are drilled correctly and could be an option.
There's a single ply white 5 hole here http://www.ebay.co.uk/itm/1-PLY-WHIT...item20dc5bbe18
The cost including shipping is under £15 and would not incur any vat, customs duty or handling charges which are extortionate for low value items.