Each RADIUS client – RADIUS server pair shares a specific password (also called a shared secret). This password must be identical on both the client and the server. If these passwords do not match exactly, the authentication or accounting packets will not be accepted by the intended recipient.
Be sure to carefully research the password (shared secret) of the RADIUS client or RADIUS server you intend to communicate with. IAS will not accept passwords with spaces and will match the case of passwords exactly.