It is probably because of one of these reasons:

• You might have typed an incorrect Recruiter ID or password. Please double-check both and try again.
• You might have typed in the wrong casing. The Recruiter ID and password are case-sensitive.
• You might not have registered yet. Upon completion of an order, you receive an email entitled, “Welcome to Yahoo! HotJobs.” That email contains a link to assign a password and secret question. You will be unable to sign into your account until you complete the registration process.
• You might be signing in as a Jobseeker rather than a recruiter. Make sure you are being prompted to enter a “Recruiter ID” rather than a “Yahoo! ID.” Sign in on the home page under the Employer Site heading at the top right corner.