It can be several issues, my guess is that flamerobin is 32bit version and is loading a old version of fbclient

try to reinstall all to be 64bit versions (Firebird 2.5.x , Flamerobin x64 ...)

http://stackoverflow.com/a/7520588/66242

ps: or it could be a wrong password

--- In firebird-support@yahoogroups.com, Ronan van Riet <ronanvanriet@...> wrote:
>
> Good morning.
>
> I am using the SYSDBA account on using Windows 7 , Firebird 2.5 (x64) and FlameRobin
>
> Here is the message I get.
>
> SQL Message : -923 Connection not established
> Engine Code : 335544421
> Connection rejected by remote interface
>
> This looks like a permissions issue, although the error message does not make clear to me which permissions need to be reviewed/added.
>
> Thanks in advance,
> Ronan
>
>
> [Non-text portions of this message have been removed]
>