He became a Professional in the year 2000, and never achieved his life's dream of becoming a Wolrd Champion.
However the question I would ask you is:
If you were his Manager when would you have Harrison fight for a World Title and against which Opponent?
To make your job easier I have listed the 4 Champions since the year 2000 to present day.
Note: The WBF and the WBU titles are not included in this:
WBC Champion:
Lennox Lewis 2000-01
Hasim Rahman 2001
Lennox Lewis 2001-03
Vitali Klitchsko 2003-05
Hasim Rahman 2005-06
Oleg Maskaev 2006-
Samuel Peter 2007-08
Vitali Klitchsko 2008-Present
WBA Champion:
Evander Holyfield 2000-01
John Ruiz 2001-03
Roy Jones Jr 2003
John Ruiz 2003-05
Nikolai Valuev 2005-07
Ruslan Chagaev 2007-08
Nikolai Valuev 2008-09
David Haye 2009-Present
WBO Champion:
Chris Byrd 2000
Wladimir Klitchso 2000-03
Corrie Sanders 2003-04
Lamon Brewster 2004-06
Siarhei Liakhovich 2006
Shannon Briggs 2006-07
Sultan Ibragimov 2007-08
Wladimir Klitchsko 2008-Present
IBF Champion:
Lennox Lewis 2000-01
Hasim Rahman 2001
Lennox Lewis 2001-02
Chris Byrd 2002-06
Wladimir Klitchsko 2006-Present
IBO Champion:
Lennox Lewis 2000-01
Hasim Rahman 2001
Lennox Lewis 2001-03
Wladimir Klitchsko 2006-present