The field used as an index is not correctly defined or is not a valid value.
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Cause . . . . . : The field used as an array index to reference an array element is not defined as numeric with zero decimal positions or is a named constant whose value is greater than the number of elements in the array; the specification is ignored.
Recovery . . . : Define the index field as numeric with zero decimal positions and ensure that it is less than or equal to the number of elements in the array. Compile again.