Hi Nuno,
I am glad you manage to get your problem solved, I read through all posts, the Country Boy told you exactly what should be done and was also very kind not telling you to read the manual. I am sure the valve was not blocked, it was probably connected on the wrong place or you reverse the polarity, a valve do not block and unblock just because it wants. Just a matter of curiosity, your English seems to me quite good, why did not you read the manual? I am sorry to ask but I am puzzled why you did not, anything against manuals