Fatal error: Class 'Lanot_EasySticker_Helper_Data' not found in /public_html/app/Mage.php on line 546

The package on Magento Connect seems to work just fine. I tested it against 1.7.0.2.

Since you said you had compilations turned on, disable that, clear your cache and try again.

Afterward, rerun your compilation.

I hope this helps.