wcf service working with 'GET' and 500 error with 'POST'

I have a wcf service that it's working well if i am using get but when i use post it's showing

System.ServiceModel.ServiceActivationException status 500

any ideas whats the error??

here is the code

function Login(e) { 
debugger; 
e.preventDefault();
//getting mail 

var loginmail = 
$("[id$='txtLoginEmail']").val(); 

//getting password

var loginpassword = 
$("[id$='txtLoginPassword']").val(); 

//getting remember me checkbox

var checked = 
($("[id$='chkRememberme']").is(':checked')); 


var proxy = new _AppProxy('MemberService/Login', '', 'xml', 'POST', '', { mail: loginmail, password: 
loginpassword, rememberMe: checked }); 

proxy.Invoke();

};


[OperationContract] 
[WebInvoke(ResponseFormat = 
WebMessageFormat.Xml,Method="POST")] 

public string Login(string mail , string password , 
bool rememberMe) 
{

}

<system.serviceModel> 

<standardEndpoints> 

<webHttpEndpoint> 

<standardEndpoint 
name="" 
helpEnabled="true" 
automaticFormatSelectionEnabled="true" /> 

</webHttpEndpoint> 
</standardEndpoints>  
serviceHostingEnvironment 
aspNetCompatibilityEnabled="true" 
multipleSiteBind开发者_开发知识库ingsEnabled="true" > 

</serviceHostingEnvironment> 

</system.serviceModel>

Can be that you miss the .svc ending in your URI to the WebService. If MemberService is the name of the service and Login is the name of the Method,

MemberService.svc/Login