Hello, I upgraded my headquarters to level 14 but can't start a rally, send me the alert to increase..

Hello. That’s strange, cause my headquarters is level 12 and I can open a rally with 5. Are you sure that upgrade the right building ?

Yes check the building. The Headquarters is the one with a moving radar on top and requires a premium resource called War Horn to upgrade.

If you have upgraded that one then there is a problem with the game. You can try using the Contact option in the in game help to contact the developers.