please set you webconfig setting like below, its work for me like charm.
<system.serviceModel>
<services>
<service name="RGB2LEDWebService.RGB2LED">
<endpoint name="http" binding="basicHttpBinding" contract="RGB2LEDWebService.IRGB2LED" />
</service>
</services>
<bindings>
<basicHttpBinding>
<binding maxReceivedMessageSize="2147483647" />
</basicHttpBinding>
</bindings>
<behaviors>
<serviceBehaviors>
<behavior>
<dataContractSerializer maxItemsInObjectGraph="2147483647" />
<serviceMetadata httpGetEnabled="true" />
<serviceDebug includeExceptionDetailInFaults="true" />
</behavior>
</serviceBehaviors>
<endpointBehaviors>
<behavior>
<dataContractSerializer maxItemsInObjectGraph="2147483647" />
</behavior>
</endpointBehaviors>
</behaviors>
<protocolMapping>
<add binding="basicHttpsBinding" scheme="https" />
</protocolMapping>
<serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" />
</system.serviceModel>