Google Chrome apps and extensions?

I have tried multiple times to install apps and themes for google chrome (portable). the first theme that i installed worked. but after that i have tried to install a gmail, google voice, weather, and one more theme. all that happens is a .crx file gets downloaded. i have tried dragging and dropping to install in the browser window. i have also tried restarting the browser. but non of that seems to work. any ideas?|||Install program and then update themes,There is limitations of portable applications.|||http://www.google.com/support/chrome/bin鈥?/a>