Hosting WCF in IIS odbc driver not found error

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IIS7

C#

ASP.NET

.NET

SQL-Server

IIS

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I have created a wcf service I run it indivudually and use that service reference it is working .
Then I hosted the service the database is not working .

this is my connection string of sql odbc database
string s = "dsn=agent1;Trusted_Connection=True";

web.config file of WCF

<?xml version="1.0"?>
<configuration>

  <system.web>
    <compilation debug="true" targetFramework="4.0" />
  </system.web>
  <system.serviceModel>
    <behaviors>
      <serviceBehaviors>
        <behavior>
          <!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment -->
          <serviceMetadata httpGetEnabled="true"/>
          <!-- To receive exception details in faults for debugging purposes, set the value below to true.  Set to false before deployment to avoid disclosing exception information -->
          <serviceDebug includeExceptionDetailInFaults="false"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />
  </system.serviceModel>
 <system.webServer>
    <modules runAllManagedModulesForAllRequests="true"/>
  </system.webServer>

</configuration>

before hosting in IIS it worked but after hosting this is error code
ERROR [IM002] [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified