The Shrimps made it six points from 39 after losing the first of two home games against sides also in League One’s bottom four.
Greg Leigh had headed Morecambe into the lead by half-time, after which two goals in seven minutes from Chris Porter and Luke Murphy gave the visitors victory.
It leaves Robinson’s players looking to rediscover the winning formula with bottom club Doncaster Rovers their visitors on Sunday.
Speaking afterwards, Robinson said: “I’m extremely disappointed.
“It was a huge game and it looked like it was a huge game for a lot of players - and a lot of them froze.
“They were hiding from the ball. We have to be brave on the ball but we weren’t and I think we got what we deserved.”
The game looked to be there for the taking with Morecambe ahead at the break, having withstood some early pressure from the visitors.
However, they allowed Tom Lowery to get into the area and cross for Porter, unmarked five yards out, to head home the equaliser.
Then, not long afterwards, a half-cleared cross was collected by Murphy, who fired a dipping effort over Morecambe keeper Kyle Letheren.
Robinson added: “We finished the (first) half well, then we started the second half well and had a couple of half-chances.
“However, if you defend like that, that’s been the story of our season: individual errors and people struggling to cope with the quality at this level.
“It’s a different player every week making mistakes. If you can’t defend, you need brave people on the ball and we didn’t have them.”
The Shrimps also had issues in attack, given they were without top scorer Cole Stockton.
A calf strain meant the striker was absent, other players have fallen victim to illness, while Adam Phillips limped off early in the second half.
Robinson added: “Cole was injured, he hasn’t got Covid.
“Hopefully he will be available but we have a couple of boys out with Covid and Adam Phillips looks like he could be injured.
“Ryan Cooney has tonsillitis, so things aren’t going our way in terms of consistency of selection and injuries - but the players on the pitch have to be better.”
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