Testing has shown problems with this combination of software. Here's why:

First, the Sonic Maximizer does not come with an RTAS (Pro Tools-compatible format).

Second, there are known problems when using the FXPansion VST to RTAS wrapper to change the VST format into a Pro Tools plugin.

Try updating all software (VST-RTAS Wrapper, Sonic Maximizer, and Pro Tools, including the latest Pro Tools CS updates) to see if this helps.