Poynt ProductService crashes

I tried to all getRegisterCatalog method of productService but I am getting below exception;

Could you please let me know why this issue is coming?

I binded the service before calling this method.

FATAL EXCEPTION: main Process: co.poynt.services, PID: 13620 java.lang.NullPointerException at co.poynt.services.tasks.product.GetRegisterCatalogTask.onPostExecute(GetRegisterCatalogTask.java:50) at co.poynt.services.tasks.product.GetRegisterCatalogTask.onPostExecute(GetRegisterCatalogTask.java:15) at android.os.AsyncTask.finish(AsyncTask.java:632) at android.os.AsyncTask.access$600(AsyncTask.java:177) at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5017) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) at dalvik.system.NativeStart.main(Native Method)

This error is returned if your IPoyntProductCatalogListener is not initialized. Please make sure you do that before calling product service’s getRegisterCatalog.