Online Sharepoint and WCF Services

Hi All,
i am new in sharepoint and working with online sharepoint using sharepoint designer.

I want to access external data in online sharepoint website.

For this i have create 1 wcf service and going to access this in sharepoint designer to make "External Content Type".
http://212.227.251.31:5659/Service1.svc?wsdl

i have Generate secure store application id  and then i am going add this service but 
getting below error.

The server was unable to process the request due to an internal error. 
For more information about the error, either turn on IncludeExceptionDetailInFaults 
(either from ServiceBehaviorAttribute or from the configuration behavior) on the server in order to send 
the exception information back to the client, or turn on tracing as per the Microsoft .NET Framework 3.0 SDK 
documentation and inspect the server trace logs.

for above error i have added  below thing in hosted web service's web config file
<serviceMetadata httpGetEnabled=”true” />
<serviceDebug httpHelpPageEnabled=”true” includeExceptionDetailInFaults=”true” />

but then also i am not able to get solution it will give us same error while adding service .
can any one please suggest for this ?