How to modify manually web application SharePoint web.config file when using asmx web service in an EventReceiver project?

Question

First of all, I need to use an asmx web service in an EventReceiver project in Visual Studio. Then, as common, I add a web reference by right click on the project and then Add menu then Service Reference... menu and finally web service url something like

and this my app.config project:

`
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <system.serviceModel>
        <bindings>
            <basicHttpBinding>
                <binding name="IntegrationService_UserSoap">
                    <security mode="Transport" />
                </binding>
                <binding name="IntegrationService_UserSoap1" />
            </basicHttpBinding>
        </bindings>
        <client>
            <endpoint address="https://???.???.??/services/???????/???.asmx"
                binding="basicHttpBinding" bindingConfiguration="IntegrationService_UserSoap"
                contract="ServiceReference1.IntegrationService_UserSoap" name="IntegrationService_UserSoap" />
        </client>
    </system.serviceModel>
</configuration>`

Then I'm going to modify web.config of the web application as I used to do like this:

<system.serviceModel>
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
        <bindings>
            <basicHttpBinding>
                <binding name="IntegrationService_UserSoap">
                    <security mode="Transport" />
                </binding>
                <binding name="IntegrationService_UserSoap1" />
            </basicHttpBinding>
        </bindings>
        <client>
            <endpoint address="https://???.???.??/services/???????/???.asmx"
                binding="basicHttpBinding" bindingConfiguration="IntegrationService_UserSoap"
                contract="ServiceReference1.IntegrationService_UserSoap" name="IntegrationService_UserSoap" />
        </client>
  </system.serviceModel>

now, when I'm going to deploy the project by visual studio I've got this error: "Error occurred in deployment step 'Activate Features': Operation is not valid due to the current state of the object." What is wrong?