Why The BaseWindowedBolt Excuted 2,428,080 But Only acked 282,380

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Dear all,
This is my code in topology.Is there has any error logic?

And this is storm-ui that I find this bug.I don't know why this bug take 
place?The Bolt excuted 2,428,080 but only acked 282,380.

Help me!
Best regards!