UpdateInterval not working correctly

Question

I fail to see why the following code does not turn the hand at the same rate as the minute hand of a clock:

DynamicModule[{incr, s},
    incr = Pi / (2.0 * 15 * 60);
    s = (Pi / 2.0) + incr;
    Graphics[{
        Circle[],
        Dynamic[
            Refresh[s -= incr; Line[{{0, 0}, {Cos@s, Sin@s}}], UpdateInterval -> 1]
            (*, TrackedSymbols :> {} stops the movement entirely *)
        ]
    }]
]

It seems that UpdateInterval has no effect. Not matter the value to which it is set, the hand moves at the same speed. And, as indicated in the comment inside the code, setting the TrackedSymbols option stops the movement of the hand entirely.

EDIT

It turns out that I simply had to quit the notebook and restart that. That solved the problem for me.

Answer 1

This works for me:

DynamicModule[{incr, s},
    incr=Pi/(2.0*15*60);
    s=(Pi/2.0)+incr;
    {
        Graphics[
            {
            Circle[],
            Dynamic[
                s-=incr; Line[{{0,0},{Cos@s,Sin@s}}],
                TrackedSymbols->{},
                UpdateInterval->1
            ]
            }
        ],
        Dynamic[s]
    }
]