Installation Problem with core component

joomlamailer version: 1.7.2
Joomla! version: 1.5.22
PHP version: 5.3.8
MySQL version: 5.1.59

Hello there,

I have a problem trying to install the core extension to my joomla site.
I get a white page error saying:

-1 - An error has occurred.
It was not possible to copy the selected file.

I checked the permissions on my folders and they are all writable!

Further more i checked the following:

1. The extension installer was successfully copied in the /temp folder
2. The folder com_joomailermailchimpintegration was successfully created in the components folder on both site and admin BUT was not copied entirely. Something must went wrong when installer tried to copy files in that directory...
3. There isn't anything in my server error log about this.

Can you help me?

I solved the problem.

I anabled FTP account, deleted the folders that were already created in site and admin components folders, made a fresh new installation and it worked!

Now I'm having a problem entering my API key but I will look other posts about this...