My EOS 7D cant focus when use Yongnuo fix lens in quick mode AF

[Ferdian]

I use canon 7D and third party Yongnuo 50mm fix lens. my camera won't pick any focus when i using auto focus in quick mode, both in view finder or live view. But when i using it in live mode AF it can pick a focus. but i can't use view finder when using this mode.

this keep happening when i using fix lens (YN 50mm mark I/II, didn't test on canon fix lens yet and hope this didn't happen)
when i using my 55-250mm it just working fine.

can someone help me

[deebatman316]

Your lens is more than likely incompatible with your camera. Look into the Canon EF 50mm F/1.8 STM lens.

[Ferdian]

Thanks for the reply

I could use it before, this just happened recently. and it's stressing me out because I've tried restarting all the settings but it's still happening.

[deebatman316]

Are you sure it fully compatible. Most older 3rd Party lenses are NOT. The reverse happens too new 3rd Party lenses don’t work properly on older cameras. But the Canon brand lenses do. So retest with a Canon lens. 

[Waddizzle]

Sounds like the lens has failed.