I can't scan NFC by asus nexus 7

[glorylife17]

I use the NFCForms in my project. I try to Installer the app for two phones. one is sony Z5, the other is nexus 7. I can use fine in sony Z5, but I can't scan in nexus 7.
nexus 7 doesn't happen in OnPause(), Why?
I try to find NFCtools, I can scan MifareClassic card in sony Z5 and nexus 7.

[glorylife17]

protected override void OnResume () { base.OnResume (); if (NFCdevice != null) { var intent = new Intent (this, GetType ()).AddFlags (ActivityFlags.SingleTop); NFCdevice.EnableForegroundDispatch ( this, PendingIntent.GetActivity (this, 0, intent, 0), new[] { new IntentFilter (NfcAdapter.ActionTechDiscovered) }, new String[][] {new string[] { NFCTechs.Ndef, }, new string[] { NFCTechs.MifareClassic, }, } ); } }

NfcAdapter.ActionTechDiscovered > NfcAdapter.ActionTagDiscovered

NfcAdapter.ActionTechDiscovered
Intent to start an activity when a tag is discovered and activities are registered for the specific technologies on the tag.

To receive this intent an activity must include an intent filter for this action and specify the desired tech types in a manifest meta-data entry. Here is an example manfiest entry:

NfcAdapter.ActionTagDiscovered
Intent to start an activity when a tag is discovered.
This intent will not be started when a tag is discovered if any activities respond to NfcAdapter.ActionNdefDiscovered or NfcAdapter.ActionTechDiscovered for the current tag.