why did yuschenko loose the 2006 election?

The coalition which won the 'orange revolution' may still form the government

http://en.wikipedia.org/wiki/Ukrainian_parliamentary_election,_2006

so it is possible to argue that he did not loose. 

Splintering of the 'pro-democracy' coalition is usual and healthy phenomenon
in emerging democracies. Before victory, there are two fronts:
all pro-democratic forces again incumbent communists. After victory, the
pro-democratic factions start competing for power in free elections.

Example of that was split of the OF into ODS (republican) and SCCD
(democratic) parties
after 1989 in the Czech Republic.

http://www.nationsencyclopedia.com/World-Leaders-2003/Czech-Republic-POLITICAL-BACKGROUND.html

Discussion
http://democracy-rising.blogspot.com/2006/03/ukraine-election-2006-analysis.html

One should also consider the fact that prevalent US view:

"Whatever the outcome, continued Western engagement with Ukraine will be vital"
http://www.washingtonpost.com/wp-dyn/content/article/2006/03/25/AR2006032500935.html

is not always accepted in other countries. The privatization which
follows a transition
to democracy leads to economical disruptions 

unemployment
http://www.ukrnow.com/content/view/7878/27/
oil supply at world market rates
sometimes civil wars and strife
privatization of local industries, often at fire-sale prices to
foreign capital and in robber barons style

These are often blames on the first post-communistic government
http://www.factmonster.com/ipka/A0108070.html


" the statistical indicators at our disposal show a country and a
people in the midst of a long period of chronic social and economic
insecurity. There must surely be better times ahead."

http://www.ilo.org/public/english/protection/ses/info/database/ukraine.htm

Because Russia is a coming power
- and he is a tosser