Issue with intent filters in AndroidManifest.xml

I am creating an unity plugin which performs in app purchase using Google Play. In the androidmanifest.xml I have specified following activity.

<activity android:name="com.plugin.IAPPurchaseActivity" android:label="@string/app_name">
<intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter>
</activity>

In the plugin I am extending UnityPlayerActivty. When I am adding new activity with same intent filters, handleActivityResult is not called for my activity. I am not sure what is the problem here. Can anybody help me in this?