airdrop does not connect to devices

Hi, I wanted to send a couple of pictures from my MacBook pro (10.11.1) to my sister's iPhone 5s with iOS 9.3.1. I had just received pictures from her phone to mine, so I figured there shouldn't be a problem.

I went to the pictures I wanted to send and put them on airdrop but her device wasn't shown on my screen. So I went to the Airdrop "app" in the finder, where you can see all the devices you are connected to but there weren't any. so I tried my phone, my dad's phone, my dads mac and my mom's phone. none showed up on the screen. So I tried to send pictures from there phones, if they could find my mac but it didn't work either. since then I have restarted my macbook 5 times, let it sit for 4-24 hours and tried the same things again.

Somehow it can't connect to devices in Airdrop but when I try to connect my phone to it via bluetooth it shows a connection. The transfer of pictures is not possible like that but at least it is shown on the screen.

How can I fix the Airdrop problem?

Thanks for your help