Problems with SOAP header

I am trying to create a Swing app that connects to a SOAP API. I have never messed around with web services so I sure this is user error :) The code below throws an error that says "Server did not recognize the value of HTTP Header SOAPAction". Any help would be appreciated.

Java Code:

import java.io.IOException;
import javax.swing.JOptionPane;
import javax.xml.soap.MessageFactory;
import javax.xml.soap.MimeHeaders;
import javax.xml.soap.SOAPBody;
import javax.xml.soap.SOAPConnection;
import javax.xml.soap.SOAPConnectionFactory;
import javax.xml.soap.SOAPElement;
import javax.xml.soap.SOAPEnvelope;
import javax.xml.soap.SOAPException;
import javax.xml.soap.SOAPMessage;
import javax.xml.soap.SOAPPart;

public class KeyMaker {

    public void getkey(String certificate) {
        
        String serverURI = "https://ecomapi.networksolutions.com/soapservice.asmx?wsdl";

        // Create SOAP Connection
        SOAPConnectionFactory soapConnectionFactory;
        try {
            //create a SOAP connection
            soapConnectionFactory = SOAPConnectionFactory.newInstance();
            SOAPConnection soapConnection = soapConnectionFactory.createConnection();

            // Send SOAP Message to SOAP Server
            SOAPMessage soapResponse = soapConnection.call(createSOAPRequest(serverURI), serverURI);

            // print SOAP Response
            System.out.print("Response SOAP Message:");
            soapResponse.writeTo(System.out);
            soapConnection.close();

        } catch (SOAPException | UnsupportedOperationException ex) {
            JOptionPane.showMessageDialog(null,
                    "Something is wrong with the SOAP API: " + ex, "SOAP API Error", JOptionPane.ERROR_MESSAGE);
        } catch (IOException ex) {
            JOptionPane.showMessageDialog(null,
                    "Something is wrong with the SOAP API: " + ex, "SOAP API Error", JOptionPane.ERROR_MESSAGE);
        } catch (Exception ex) {
            JOptionPane.showMessageDialog(null,
                    "Something is wrong with the SOAP API: " + ex, "SOAP API Error", JOptionPane.ERROR_MESSAGE);
        }
    }

    private SOAPMessage createSOAPRequest(String serverURI) throws Exception {
        
        MessageFactory messageFactory = MessageFactory.newInstance();
        SOAPMessage soapMessage = messageFactory.createMessage();
        SOAPPart soapPart = soapMessage.getSOAPPart();

        // SOAP Envelope
        SOAPEnvelope envelope = soapPart.getEnvelope();
        envelope.addNamespaceDeclaration("urn", serverURI);

      /*
      <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:urn="urn:networksolutions:apis">
       <soapenv:Header>
        <urn:SecurityCredential>
              <urn:Application>MyApplication</urn:Application>
              <urn:Certificate>e5fd81293084376d9b326012e483</urn:Certificate>
            </urn:SecurityCredential>
          </soapenv:Header>
         <soapenv:Body>
        <urn:GetUserKeyRequest/>
       </soapenv:Body>
      </soapenv:Envelope>
     */
        
        SOAPBody sb = envelope.getBody();
        SOAPElement soapBodyElem = sb.addChildElement("GetUserKeyRequest", "urn");
        
        MimeHeaders headers = soapMessage.getMimeHeaders();
        headers.addHeader("SOAPAction", serverURI);
        headers.addHeader("urn", "SecurityCredential");
        headers.addHeader("urn:Application", "Inventory Adjuster");
        headers.addHeader("urn:Certificate", "c8678798982726367281919176632");
        
        soapMessage.saveChanges();
        
        /* Print the request message */
        System.out.print("Request SOAP Message:");
        soapMessage.writeTo(System.out);
        System.out.println();
        
        return soapMessage;
    }
}