Remember Password - Firefox - reset

[Nigel Ridley]

I opened an account at a particular website ans at the time Firefox asked if I want it to 
remember the username/password -- I clicked 'Not Now'. But now I do want it to remember the 
username/password but Firefox doesn't ask anymore.
How can I get Firefox to ask again?
I have already poked around in the preferences, unchecking and rechecked the 'Remember passwords 
for sites' option but to no avail :-(

Any pointers?

Blessings,

Nigel