Resolution:
The following list of expressions is not supported when creating scripts for the EAI Script Step (these functions work in a regular script object).

DBWRITEFIELDS    UNIXEXEC    WINMAXIMIZE
VLDQUERY    GETHANDLE    WINMINIMIZE
VLDFILE            FORMCONTROL    SENDKEYS
VLDFILEX    FORMMAXIMIZE    MEMOFILE
DDEINITIATE    FORMMINIMIZE    WINMESSAGE
DDETERMINATE    FORMRESTORE    FILEREQUEST
DDETERMALL    FORMMOVE    MESSAGEBOX
DDEXECUTE    FORMSIZE    ATTACHFILENAME
DDEPOKE            WINEXIST    MARKFIELDCHANGED
DDEGETNAME    WINACTIVATE    WRITEFIELDS
DDEGETTOPIC    WINCLOSE    READFIELDS
WINRUN            WINMOVE            WINFIND
SERVERRUN    WINSIZE            WINACTION
SERVEREXEC    WINRESTORE    CUSTAUDIT
UNIXRUN            WINMAXIMIZE    CASESTART
TRIGGEREVENT    CASECLOSE    GOTOSTEP