Automatic Bluetooth device problems

we're getitngs problems whit this so..

we need your help

the idea for this app is make this one shows a imagen when conect a specific bluetooth device, but all times that we tested appears a message that says error canno concet the argumet

we think the X=X was the problem but we don`t know hot to solve it

we really aprreciate your help

and also sorry for the bad english here