DB not working once db_cache was set to FALSE

[eluser]smilie[/eluser]
Hi,

I have enabled DB caching in config > database.php

This worked nice.
Then - I decided to turn cache off, by setting:
$db['core']['cache_on'] = FALSE;

But, once I have done that, I do not get ANY result back from the database
Just like a DB is empty (which it is not).

WTF? )

Where did I took wrong turn here?

Thanks!
Smilie