programming attiny with uno - error in upload

I made the shield according to the scheme and pics... Uploaded ArduinoISP and plugged the shield while not connected to USB... Later plugged the shielded arduino to usb and opened Blink example, selected Attiny85@1Mhz from board list and tried to upload sketch with no luck... It says:

My error is

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.02s

avrdude: Device signature = 0x000000 (retrying)

Reading | ################################################## | 100% 0.02s

avrdude: Device signature = 0x000000 (retrying)

An error occurred while uploading the sketch
Reading | ################################################## | 100% 0.02s

avrdude: Device signature = 0x000000
avrdude: Yikes! Invalid device signature.
Double check connections and try again, or use -F to override
this check.

avrdude done. Thank you.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Can someone why invalid device signature ?

I changed another UNO board, the PC capture different USB port number. But the same invalid devices error happen. I really think this is real not user friendly.

It is working now. I found out the problem is due to connection error. Thank you for clarifying.