Cracking plaster around old door

[D4N1EL]

Hi,
I've closed off a door way with a plaster board, i made abit of a frame for support. Any way the plaster between the wall and frame has now cracked although not big cracks they are noticeable. My question is:- If i rake it out, fill and sand, will it re-crack? will i just be best to paper over it of is there some kind of un-crackable paint on the market?

Thanks

 

[Bosswhite]

When did you close off the doorway, it sounds like plaster shrinkage when the plaster dried out, did you tape the joint between the plasterboard and original wall ?
rake out cracks and fill with fine surface filler.

 

[D4N1EL]

I boarded it up and plastered it mid sept, cracks started to appear soon after it had dried. I honestly cant remember if i used skrim or not (is it called skrim?)