Valencia coach Ruben Baraja was left frustrated with the match officials after defeat at Barcelona.
Raphinha struck early for Barca which also saw Ronald Araujo sent off.
Baraja said: "We leave here empty handed. I can't be happy when we leave here with zero points. Today we had an opportunity to continue picking up points and give continuity to game that we had against Real Sociedad game. At times the team had situations to go level, but we didn't have the shot in the final metres. The team has worked well, we were alive in the game, we had our chances and it's a shame that we come away with nothing."
On the penalty appeal for Fran Pérez, Baraja said: "We have been able to see the footage and there is a contact. The assessment is that there is contact and then the interpretation is up to the referee to decide -and he decided that there was no penalty. We cannot go into it, because it is their assessment.
"It's like the penalty given against us for handball by Hugo. There is a very fine line between getting it right and wrong. What surprised me was that they didn't consider the possibility of checking VAR, as they did the other day at Mestalla. That means that we don't know how they do things in such situations. The contact is there, then we need to see if they call a penalty or not, which depends on the referee and VAR. Them not looking at it surprised me.'
Baraja also said: "We tried to stay in the game and we had chances, but when you have situations and you don't score, you are up against it. They scored from their first chance. We had some clear chances like that for Samu Lino, but the ball didn't go in.
"We modified things after the sending off to have more players near the final third, because we dominated the game and we had two or three clear chances - but if you don't finish them off, you cannot score points.
"We have to insist on the continuity of the work that we did against Real Sociedad, add to that the positives from today and believe that the next game is the most important. This one had already been and gone. We had our chances and we competed, but we lacked the finishing that determines the result.
"The next game at Mestalla is vital in every way."
