On Sun, 10 Jul 2016 07:50:06 -0700 (PDT), trader_4
wrote:

We don't know what kind of compound, board, etc.
New or had they been sitting around, surface possibly soiled, etc?

OP hasn't stated how well he mixed the compound prior to application.
It should not be taken from the container and slapped on the wall.
Always mix it well. and during application.