FATAL EXCEPTION : Caused by: java.lang.RuntimeException: instance cannot be null. call start first.

[shridhar49]

I am getting below exception while calling ChatUI.getInstance().openConversationMessagesActivity("XXXXXXXXXXXXXXXXXXX", "XXXXXX");`

Caused by: java.lang.RuntimeException: instance cannot be null. call start first. at org.chat21.android.core.ChatManager.getInstance(ChatManager.java:409) at org.chat21.android.ui.conversations.fragments.ConversationListFragment.onCreate(ConversationListFragment.java:114) at android.support.v4.app.Fragment.performCreate(Fragment.java:2339) at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1377) at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1740) at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1809) at android.support.v4.app.FragmentManagerImpl.dispatchStateChange(FragmentManager.java:3217) at android.support.v4.app.FragmentManagerImpl.dispatchCreate(FragmentManager.java:3166) at android.support.v4.app.FragmentController.dispatchCreate(FragmentController.java:181) at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:319) at android.support.v7.app.AppCompatActivity.onCreate(AppCompatActivity.java:84) at org.chat21.android.ui.conversations.activities.ConversationListActivity.onCreate(ConversationListActivity.java:17) at android.app.Activity.performCreate(Activity.java:6259) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1130) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2490)  at android.app.ActivityThread.-wrap11(ActivityThread.java)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1354)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:148)  at android.app.ActivityThread.main(ActivityThread.java:5443)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)