Replace footage wont work

[Asaf24660910x6ea]

As i'm trying to replace footage for pre synced proxies every thing work's just fine. but when same Im doing same thing on synced to sound proxies videos. "Replace footage" painted in grey unclickable. 

picture is attached. 

TY

[Kevin-Monahan]

Hi Asaf,

Sorry about that. I do not fully understand your workflow. Are you using merged clips? If so, that may be the issue. Let us know more details 

Thanks,
Kevin