An air carrier Dispatcher reports he missed the Daytime Operation only Restrictions for an EMB-145 under their MEL Chapter 33. Lack of communication between the Flight crew; Maintenance and himself as the Dispatcher cited as contributors.

Narrative

January 2010: Flight XYZ is a round trip from ZZZ to ZZZ1. The event involved an EMB-145LR. I had that aircraft for the entire night. What happened was Maintenance was on the aircraft and added an MEL prior in the day. The MEL that was supposed to be added was MEL number: 33-50-00 with that MEL there is a Daytime only restriction. This plane flew 3 legs in the evening and morning hours when it was dark outside. But looking over the Releases; it looks as if the MEL was put in wrong and may have been put under the MEL number: 33-26-00 which there is no significant restriction associated with that MEL. It looks as if on the next leg the MEL's were changed to being correct on the release. I missed the change of MEL's and therefore missed the Daytime operation only restriction associated with this MEL. It was also a bad weather day and it was hard to find Alternates and the phone was non-stop so I kept getting distracted every time I needed to do something; because every time I tried to do something another flight would need something or another issue would be going on that I needed to look at. I think the event occurred because there may have been a lack of communication between the [Flight] crew; Maintenance and myself as the Dispatcher. I feel that we weren't on the same page with the MEL. I also should have looked at the MEL closer and realized that they had changed and looked up the new one and not have been trying to multi-task at the time of the event.