Sometimes we just hit a plateau and we have to accept it. Just keep working, take some time to look back at what you have learned and done so far.
Perhaps you should take a break from it. Stop trying to force the connection. Rest for a week or so and try it again.
There are many causes of this, each individual who experiences it has a different cause, sometimes many causes. Don't focus on it as a bad thing, see it as a point of growth or a change of path. Don't force yourself to correct it.