The Debugger cannot interpret a reference to a substring of a character value. Two numbers in square brackets specify a substring, as in the following expression:
charvalue[n1,n2]
The name charvalue must be the CHAR(n) data type; n1 specifies the first character of the substring, and n2 specifies the last. This error message appears when n1 is larger than n, the length of the character value, or when n1 is greater than n2.