Using [[PlanningFunctions.getIdForString("text")]] within a calc script in a groovy script

Hello, I am trying to save some data into a Text field using the PlanningFucntions.getIdForString within a Calc script, that is nested within a Groovy script. I have been able to successfully do this within a normal Calc script but so far I have been receiving an error - "Calc script execution failed for BA000364: Error parsing formula for [BA_SRCFD] (line 0): expression expected after []"

I have included a snippet of my code, mainly focused on the creation of the Calc script. Below that is the message log when running the script. As far as I can tell everything about my variables should be right but I'm clearly running into some issue.