WCF: IIS Log sc-status=400 and sc-win32-status=64. [Clinet application does not respond]

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C#

IIS

WCF

I have deployed WCF services on IIS 7.5. When i request to Service, It hangs up client application, nothing respond from WCF Service. When I visit IIS Log I got sc-status=400 and sc-win32-status=64.

This case is reproduced on production environment. I tried to reproduce on my machine, but i can't. Moreover i am failed to find some helping material by googling.

Can any body provides in detail, whats root cause, and how can i reproduce at my machine.

Bellow is IIS log for your information

2014-07-10 00:07:21 53.90.35.187 POST /SyncService.svc - 8000 - 53.90.36.144 - 400 0 64 129764
2014-07-10 00:55:05 53.90.35.187 POST /SyncService.svc - 8000 - 53.90.36.144 - 200 0 64 78
2014-07-10 01:45:18 53.90.35.187 POST /SyncService.svc - 8000 - 53.245.9.162 - 200 0 64 639
2014-07-10 02:00:17 53.90.35.187 POST /SyncService.svc - 8000 - 53.245.5.60 - 200 0 64 514

Thanks in advance