Default [Q] Help needed for Bluetooth 4.0 connection

Since Android 4.3, Bluetooth 4 is supported if the device supports it as well. The i9500 has this ability.
As I am a running addict, I bought a compatible heart rate monitor belt with dedicated ability to be connected to the s4. Link:

Unfortunately, I can not pair it with my s4. The device is simply not recognised. I followed the connection instructions but failed repeatedly. I don't have problems with other Bluetooth devices (most likely Bluetooth 3).
I debloated the stock rom mj8 and am not sure if there are particular files ONLY for Bluetooth 4, which I might accidently deleted. I can not imagine that, but maybe somebody can enlighten me.

I9500, stock 4.3 mj8, rooted

Thanks for your help in advance.

Edit: Due to the fact that 100 viewers but no reply to this post: Did anybody EVER successfully pair a BT4.0-device with the S4?