You're not the first person to post such a question, and we don't know. You're asking about a situation in a specific channel. The place to ask about a problem in that channel is to ask - in that channel. Or in a similarly named channel where the 'regulars' can chat. With having zero knowledge of the situation, you could have run afoul of a new rule change that we could not possibly know of.

Some networks have been combatting spam by defaulting to giving modes which prevent being private messages and CTCP's between users where at least one of them is not identified to nickserv with a password. Try the following command in an editbox and compare the list of letters displayed from their definitions when you google irc user modes and possibly also including the name of your network.

//echo -a $usermode