> The following script
> ---
>
> C:\>cd\program files\firebird\firebird_1_5\bin\
>
> C:\Program Files\Firebird\Firebird_1_5\bin>gbak -b -se
> localhost:service_mgr localhost:myalias c:\test.fbk -user sysdba
> -password masterke -v
>
> C:\Program Files\Firebird\Firebird_1_5\bin>

Using service API you don't need to put host name into connection
string. Try

gbak -b -se localhost:service_mgr myalias c:\test.fbk -user ...

Regards,
Vlad

PS Also consider to include switch -g doing backup