HaProxy with "Proxy-Authorization"

Job ID: 31973496

Budget: $10 – $30 USD

I'm trying to make HaProxy require a "Proxy-Authorization" header with user/password.
I tried something like
>> reqadd Proxy-Authorization:\ Basic\ dXNlcjpwYXNz

But that is not working. I got this error
https://gyazo.com/0f52c95a98e59f6d62b48dadd3feeec2

OS: Debian 10
Related categories: System Admin Linux Debian