[help needed] - goto realtime context

I’m having troubles with the command ‘goto’ in the dialplan;

whenever I try to (for example) goto(extensions|1000|1), and the context ‘extensions’ is a realtime one (aka loaded into, in my case, MySQL) it won’t work; in the logs I can find a line corresponding with the problem:

WARNING[pid] pbx.c: Channel ‘SIP/1001-8586’ sent into invalid extension ‘1000’ in context ‘extensions’, but no invalid handler

Can anyone offer some advice? Thank you.