Chavez won't play ball with the US, and has aligned himself with the US's greatest thorn in the side in the Region, Cuba, as well as flirting with Russia.
He survived the 2002 Coup attempt (Which may or may not have had US backing), maintains popular support from the grass roots of Venezualan society (If not the Middle classes) and won't relinquish control of all that lovely oil he has.
He also appears decidedly ungrateful for all of those lovely F-16's Venezuala was sold.
It is no surprise that Venezuala is coming under increasing pressure from the regions (worlds?) only superpower to get in line.
It is after all, "America's back yard"
I know, I read too much Chomsky