Stalled Fermentation

[brianbrewed]

Started a batch of American Brown Ale last Thursday.
I pitched a sachet of Safale S-04 and as usual it took off very quickly (within 12 hours).
However it airlock activity has died down yesterday (Monday).
When I took a sample I got a hydrometer reading of 1022.
I gave the fermentation vessel a shake and stuck on a heat belt.
Measuring today it seems to have dropped to 1020 or so.
Airlock activity still zero though.
Anybody any thoughts?

The grain bill was as follow

Lager Malt 4.7kg
Vienna 650g
Chocolate 280g
Crystal 40 280g
Crystal 60 280g

Hops

Admiral 36g 60mins
EKG 30g  30mins
Hallertau Trad 14g 

OG 1056
projected FG 1014

[phynes1]

Give it another couple of days.

Even though there is no visible fermentation, likelihood is the yeast isn't finished yet.

[Dunkel]

Could just be a leak around the airlock grommet.

[DEMPSEY]

Don't always rely on them bubbles as they can often have a leak so the excess gas may be getting out elsewhere.