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)