In xcode7, Xcode cannot run using the selected device, and the actual machine test cannot be performed.

I heard that the actual machine can be tested free of charge with Xcode7, so I tested the actual machine with Xcode7.
Then, as the title suggests,

Xcode cannot run using the selected device.

The actual machine test is not possible because it came out.
Also,
in the emulator selection section The ineligible device says unavailable, and even if you choose it and try to test the actual machine,

Could not find Developer Disk Image

That's what happens.
Please tell me the solution.

·Specs of OS and actual equipment used
Xcode7beta
MacOs:10.10.4
IOS live: iphone 4s IOS 8.4

·Setting Xcode
IOS deployment target: 8.4