Okuma Alarm-B 2229 EXPRESSION right side

Okuma Alarm-B 2229 EXPRESSION right side
On the right side of equation, an unusable command was specified; a command other than numeral, input variable, system variable, common variable, local variable, or extended address character. Input variable: variable effective in signal input from external equipment [variable number]
System variable:system-defined variable that the user cannot rename
Common variable:variable commonly used in main and sub programs
<2 numerals>
Local variable:variable named and used by the user
<2 alphabetic characters><2 alphanumeric characters>
Extended address character:NC-defined variable expressed in two alphabetic characters

Object
SYSTEM

Code
Specified factor classification code

Probable Faulty Locations
Right part of the expression
Program Example:
VDOUT [31] = VDOUT [31] + 1

Measures to Take
Correct the error at the right part of the expression.
Example: VDOUT [31]=1