Error while deploying a Service Group

1) I have created a new class "CustomCurrencyService" with the following code:

class CustomCurrencyService
{
}

[SysEntryPointAttribute]
public CurrencyName getCurrencyName(CurrencyCode _currencyCode)
{
   return Currency::find(_currencyCode).Txt;
}

Changed the class property RunOn to "Server"

2) In the AOT, I have created a new service with the following properties:

Then, I have added the operation by selecting getCurrencyName from the "Add Service Operation" Form. 

Step 3:  Once the service is ready, I have created a Service Group named  "CustomCurrencyServices" and then created a created a new service nodereference with the following properties:

Step 4:  Once the service group is ready with one service node reference, I am trying to "Deploy Service Group".  But I am getting the below error:

"The port 'CustomCurrencyServices' could not be deployed.\nError: 
c:\Users\ServiceAccountAX\AppData\Local\Temp\ServiceGeneration\CustomCurrencyService.cs(34,19) : error CS0234: The type or namespace name 'CustomCurrencyService' does not exist in the namespace 'Dynamics.Ax.Application' (are you missing an assembly reference?)
c:\Users\ServiceAccountAX\AppData\Local\Temp\ServiceGeneration\CustomCurrencyService.cs(34,61) : error CS0234: The type or namespace name 'CustomCurrencyService' does not exist in the namespace 'Dynamics.Ax.Application' (are you missing an assembly reference?)"

Not sure what needs to be done with this error, could any one please help.

Also in the Inbound Ports form, I am able to see the "CustomCurrencyServices" port name but there is no WSDL URI for this and also I am not able to activate this port.