You 'did' put these scripts ABOVE your battlesystem, right?
The SDK alters and replaces the default RGSS scripts, and as such must be placed above any and all custom scripts. As Slipknot's message system is an SDK script, it goes below the SDK but above any non-SDK script such as your battlesystem.
Off-Topic (no reply expected :D ):
Also, line #172 and not #191? Either you're using an older version of RTAB (which is currently version 1.16), an edited version of RTAB, or some battlesystem which is ripping off Cogwheel's Gauge_Rect function.
Yes, RTAB can work with SDK 2.2+. It's just that it must go below the SDK as its functions take over and replaces the SDK's battlesystem code. That's common with any Non-SDK script including various battlesystems.