What version of eCart do you have?
Make sure you have eCart 6.0.6 installed. if you have a previous version installed, make sure to uninstall it from the extension manager before installing a newer one.
I see a few different errors reported in this thread, so when you say you have the same problem it is a bit difficult to know which one you refer to.
if you continue to have a problem, please start a new thread with specifics.