Sender file adapter conversion Error!!

Hello every one....

I am stuck with a problem...in my scenario,, there are possiblities that file may contain more than required paramters... in such case,,, paramters defined in conversion should go ahead and others should be ignored...

for this very purpose i added the paramter:

row.fieldSeparator ,

row.fieldNames orderno,authcode,status

row.endSeparator 'nl'

row.additionalLastFields ignore

the scenario works fine if the file contains thrree comma separated values but it raises an error if no of paramters increase as :

Conversion of file content to XML failed at position 0: java.lang.Exception: ERROR converting 
document line no. 1 according to structure 'row':java.lang.Exception: ERROR in configuration: more 
elements in file csv structure than field names specified!

we are using PI 7.... does it require some more configuration in additoin to paramter row.additionalLastFields

any help in this regard would be highly appreciated...

thanx