this is a limit on the memory usage set by the server.
try adding the following code to the webassist/caching/PG_CachedResize_Image.php at line 1:
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.