Send a note to our techsupport - they can help you troubleshoot this.
The issue with your equation is the second quote in '*''.
When working with PI Performance Equations, Performance Equation Reference Manual (%PIHOME%\Help\PEReference.chm) is always a good resource.
You can use pipetest.exe to test your equations, maybe together with the Performance Equation builder add-in for PI SMT. pipetest.exe returns better information at what position the error is found.