We’ve recently bought an older house and have had a full house skim. The fresh plaster has been left for minimum of 4 weeks and appears totally dry. When we’ve started painting a mist coat there appears to be some areas which aren’t covering too well and appear patchy. The mist coat doesn’t flake off the patches when I’ve checked. Is this something that a second mist coat would fix or the first top coat for example? Otherwise do I need a further primer? There does also appear to be some patches from PVA drips when the plasterer has been prepping nearby walls/ceilings, again would the treatment for these be the same? I’ve attached some pictures for reference.