Salaam Agha the whole country of uganda is celebrating eid tomorrow while we will continue with our 30th ramazan. why cant we celebrate eid with fellow brothers ? what are the rules which apply for eid moon.

Because moon was not sighted Uganda is following announcement of Saudi Arab in Pakistan and other part of the world west and east those who are following ruling of sighting they are not celebrating Eid
Below is the ruling for the Eid
If a person himself sights the moon. If a number of persons confirm to have sighted the moon and their words assure or satisfy a person. Similarly, every other thing which assures or satisfies him about moon having being sighted. If two just (Adil) persons say that they have sighted the moon at night. The first day of the month will not be established if they differ about the details of the new moon. This difference can be either explicit or even implied. For example, when a group of people goes out in search of a new moon and none but two Adils claim to have seen the new moon, though, among those who did not see, there were other Adils equally capable and knowledgeable, then the testimony by the first two Adils will not prove the advent of a new month.
(iv) If 30 days pass from the first of Sha’ban , the 1st of Ramadhan will be established, and if 30 days pass from the 1st of Ramadhan the 1st of Shawwal will be established.