telegram not sending to some groups

some groups limit access for bots, are you the manager of group?

yes. how can I check that?

Finally I get it!!! ??

In order to activate the bot, you need to get the Id/title of the chat (group). Please see: https://stackoverflow.com/questions/32423837/telegram-bot-how-to-get-a-group-chat-id-ruby-gem-telegram-bot

then you must write a new Post in WP and select:
* Full URL
* Post Content
* No Image (or other option, but remember that if there are not a photo, the message will not sent)

It’s not necessary that the bot is Admin in the group

if you check the Channeller Plugin description you will find this useful bot:

Notice: add @Channeller_Bot robot to your group to get the Group ID, your bot should be one of the Group members for sending messages.