Can I still track my iPhone 6s plus with Find My iPhone if there's no SIM card?

My second iPhone 6s plus was recently stolen. It was my extra one for home use and I only used it on Wi-Fi at home so it had no SIM Card. I had Find My IPhone on. But it doesn't seem to be working. Is this because there's no SIM? I never thought about it potentially not working without a SIM.

Nope, no sim no work

Will only work if the phone, ipod touch or iPad is connected to the internet with or without a Sim card. Also location (gps), sbould be turned on as well.

Yes but the phone needs to be connected with the internet.