Why squid authentication fails?

I'm trying to add authentication to squid installed on windows, here is the config:

auth_param basic program C:\Squid\lib\squid\basic_ncsa_auth.exe C:\Squid\etc\squid\.htpasswd
acl ncsa_users proxy_auth REQUIRED
http_access allow ncsa_users

http_port 2001

http_access allow localnet
http_access deny all

In .htpasswd

admin:$apr1$kWA/DRFy$klaeXRe3S3jIPqc64HTMA0

This corresponds to username admin and password 1234

But once I try to use the proxy, got TCP_DENIED/407 in logs, and auth fails.

Update:

found the following error in log C:/Squid/lib/squid/basic_ncsa_auth.exe: error while loading shared libraries: cygcrypt-2.dll: cannot open shared object file: No such file or directory