If you using multiple database then you have to give seperate session-factory.
your error says that there is no connection provider.
so, just check your nhibernate.cfg.xml (for availability of connection provider)
refer below config file code (and change config file according to that).
<hibernate-configuration xmlns="urn:nhibernate-configuration-2.2-x-factories">
<session-factory name="Development">
<property name="connection.provider">NHibernate.Connection.DriverConnectionProvider</property>
<property name="dialect">NHibernate.Dialect.MsSql2008Dialect</property>
<property name="connection.driver_class">NHibernate.Driver.SqlClientDriver</property>
<property name="connection.connection_string">Server=Sql01;DataBase=dbABC1;uid=A;pwd=A123</property>
<property name="show_sql">true</property>
<mapping assembly="DataLayer" />
</session-factory>
<session-factory name="Production">
<property name="connection.provider">NHibernate.Connection.DriverConnectionProvider</property>
<property name="dialect">NHibernate.Dialect.MsSql2008Dialect</property>
<property name="connection.driver_class">NHibernate.Driver.SqlClientDriver</property>
<property name="connection.connection_string">Server=Sql02;DataBase=dbABC2;uid=A1;pwd=A1234</property>
<property name="show_sql">false</property>
<mapping assembly="DataLayer" />
</session-factory>
</hibernate-configuration>