title: sagepay java configuration gives me below error after clicking on Form Kit link
body: <p>java.lang.NullPointerException
      at com.sagepay.sdk.api.util.CryptographyHelper.AES(CryptographyHelper.java:41)
      at com.sagepay.sdk.api.util.CryptographyHelper.AESEncrypt(CryptographyHelper.java:63)
      at com.sagepay.sdk.demo.FormKitHandler.isEncryptionPasswordOk(FormKitHandler.java:143)
      at com.sagepay.sdk.demo.FormKitHandler.welcome(FormKitHandler.java:130)
      at com.sagepay.sdk.demo.FormKitHandler.dispatch(FormKitHandler.java:80)
      at com.sagepay.sdk.demo.FormKitServlet.dispatch(FormKitServlet.java:19)
      at com.sagepay.sdk.demo.AbstractKitServlet.dispatch(AbstractKitServlet.java:78)
      at com.sagepay.sdk.demo.AbstractKitServlet.doGet(AbstractKitServlet.java:62)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
      at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
      at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
      at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
      at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
      at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
      at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
      at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:957)
      at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
      at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
      at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
      at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:620)
      at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2516)
      at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2505)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
      at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
      at java.lang.Thread.run(Thread.java:722)</p>