I wonder what's wrong with the pool.

My rig shows its normal hasrate:

(5s):2.633M (avg):2.562Mh/s | A:40448  R:0  HW:0  WU:2175.2/m  WUE:84.9%

But pool statistics shows NULLs for a hour:

Hash Rate: 0.00 kH/s

Recent Shifts
ID    Ended    Shares (yours / total)    Blocks Found
6086    OPEN    0 / 957528    0
6085    2014-02-16 18:02:07    0 / 15059984    25
6084    2014-02-16 17:47:52    0 / 15074768    23
6083    2014-02-16 17:33:37    0 / 15051088    23
6082    2014-02-16 17:19:27    0 / 15095968    35

Are my shares counted? Hope I'm not sending my precious shares to the void...