Midfielder Matthew Saunders' 17th-minute strike proved enough to condemn the Bees to defeat and keep them bottom of the table.
Robson said: "We didn't create enough chances unfortunately, but at 1-0 we always thought we could get something.
"We knew it was going to be a tough game because Dagenham have been doing well and of course there was extra spice with it being a derby.
"We're just disappointed that we've not taken anything from the game. We played well in patches but didn't give ourselves enough chances to score.
"Their goal was a good one but we could have done better to prevent it.
"It's no secret it's tough being at the bottom, but we've got enough quality in this squad to get out of trouble."