SAP Note 21179 - Dynamic fld spec. with length lead to syntax error

Symptom:

Syntax error during a dynamic field specification with length
Error message: "(f(l))" is no valid dynamic specification ...

Cause and prerequisites

The structure analysis of a field of the form "(f(len))" is incorrect.

Solution
Due do compatibility considerations, the problem will only be corrected in 4.0. There can be problems with fields which contain a closing bracket.
Preliminary correction:
Assign the field containing the length specification to a help field and use this field to work with.