Composite index problem

This code is fine is SQL "select field1 || field2 as field1and2 ok in SQL but how in 4gl ? I am trying to overcome a problem where the table has a multi-part index on the 1st 2 fields (I cannot change this) and keep on getting the error " 245: Could not position within a file via an index. 103: ISAM error: illegal key descriptor (too many parts or too long). What I really want to do is "select * from table where field1 = value" but since field1 is part of an index this appears to cause the problem - why. How can I overcome this? Thanks in advance. Derek Ruskin Derek Ruskin