You do not have sufficient privlages to access the Blockland folder.
For Windows:
If you're running Vista: Go into "Compatibility", under "Properties" of Blockland as an Administrative account. Make sure the "Run as Administrator" box is checked on.
If you're running NT/XP: You must be a Computer Administrator account type, and not have the Screenshot's folder Read-Only.
If you're running 98/SE, 95, 2000: loving update your computer. Get with the times.