Wcf service call from powershell

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PowerShell

WCFService

Hi all,
I would like to call WCF service from powershell. Given below is my code.

$url = "http://abc.com/abc.svc"
try {
$myService = New-WebServiceProxy -Uri $url -ErrorAction Stop -Namespace "WebServiceProxy" -Class "USZip"
$myService | Get-Member -Name TestforSUMO
$myService.definition
(This works fine so I am able access WCF methods)

$result = "false"
$resultSp = "false"

$myService.TestforSUMO("Test",[ref]$result, [ref] $resultSp)
Write $result
}
catch [System.Net.WebException]{
Write ([string]::Format("Error : {0}", $_.Exception.Message))
}


But TestforSUMO method gives Error: The request failed with HTTP status 400: Bad Request.

I am not getting what is a problem. Please help me.

Code of svc.cs
___________________
[WebInvoke(Method = "GET", BodyStyle = WebMessageBodyStyle.Wrapped, RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json)]
public void TestforSUMO(string InputString, ref Boolean OutputString)
{
OutputString = true;
}

In WCF config file _____________

<behaviors>
      <endpointBehaviors>
        <behavior name="CommercientclientAPI.Service1Behavior">
          <webHttp />
        </behavior>
      </endpointBehaviors>
      <serviceBehaviors>
        <behavior name="">
          <serviceMetadata httpGetEnabled="true" httpsGetEnabled="true" />
          <serviceDebug includeExceptionDetailInFaults="true" />
        </behavior>
      </serviceBehaviors>
    </behaviors>

What I have tried:

Did some changes in Webconfig file