If you are using the embedded (HSQL) database then the tables are not created correctly.

Modify /plugins/asterisk-im/database/asterisk-im_hsqldb.sql to read as below, restart openfire and try to add a server again - hopefully it will work for you.

create table phoneServer (

    serverID bigint not null,

    serverName varchar(255) not null,

    hostname varchar(255) not null,

    port integer not null,

    username varchar(255) not null,

    password varchar(255) not null,

    constraint phoneServer_pk primary key(serverID)

);

create table phoneDevice (

   deviceID bigint not null,

   device varchar(255) not null,

   extension varchar(255) not null,

   callerID varchar(255),

   isPrimary integer not null,

   userID integer,

   serverID bigint not null,

   constraint phoneDevice_pk primary key (deviceID)

);

create table phoneUser (

   userID bigint not null,

   username varchar(255) not null,

   constraint phoneUser_pk primary key (userID)

);

create unique index phoneUser_username_idx on phoneUser(username);

INSERT INTO jiveVersion (name, version) VALUES ('asterisk-im', 2);