record: Parameter value is not valid.

Sorry to be such a pest with these keyed files, but I am having a problem again.
I am reading a record from a file, and then immediately updating the record in
the file without changing the contents - just as a test to see if I can update
the record.  It is throwing an exception and giving me the error message:
record: Parameter value is not valid.  What is it trying to tell me?

Here is the code snippet:

try {
              ContlFile.open(AS400File.READ_WRITE, 0,
AS400File.COMMIT_LOCK_LEVEL_NONE);
              Object[] keyObj = new Object[]{new String("SH00001")};
              CNTLRecord = ContlFile.read(keyObj,
com.ibm.as400.access.KeyedFile.KEY_LE);
              if (CNTLRecord != null) {
                   String tempSeqNumber = (String)CNTLRecord.getField("COSEQ");
                   seqNumber = Integer.parseInt(tempSeqNumber);

                   ContlFile.update(keyObj, CNTLRecord);
                   System.out.println("sequence number " + seqNumber);
              }
              ContlFile.close();
          } catch (Exception e) {("sequence
               System.out.println("Problems with the control file " +
e.getMessage()); // this is where it is telling me record: Parameter value is
not valid.
               try {
                ContlFile.close();
              } catch(Exception f) {
            }
          }

Amy