Wp-login.php not working/ Reverse Proxy from Windows Server

Hi,
Recently I moved our blog from blog.domain.co.uk to domain.co.uk/blog. Our main website http://www.domain.co.uk is published on windows server(IIS 7.0, ASP.Net), from that server I am accessing our wordpress blog, which is published on Linux server, through reverse proxy on webserver. Blog is working fine, but when I tried to login wp-login.php, it is redirecting to domain.co.uk/wp-admin with 404 error(I expect it should be domain.co.uk/blog/wp-admin). Can anyone please help me to fix this issue?

Thanks,
Dony