API ::: Error - Not logged into Proxmox Host. No Login Access Ticket found or Ticket

Hi all,

we would test proxmox-API, but if we would login we get the message: Error - Not logged into Proxmox Host. No Login Access Ticket found or Ticket Expired. Logininformation are correct. We have a cluster and login to cluster with pve login-informations. What can we do to login correctly?
cluster log said:
authentication failure; rhost=217.65.130.114 user=admin@pve msg=invalid credentials

In password we have special character - it´s a problem with authentication. character "!" does not work, bu why?

please help. very thanks.

regards