reading a keyed file

hi,

i'm trying to read a file with a key. there is no problem if i try to read some 
records in the middle of the file. but if i want the first record i get the 
following error:

class com.ibm.as400.access.AS400Exception : CPF5001 null

i'm using the method: keyedfile.positionCursorBefore(key,numberOfKeys)

i don't get the error if i use the method:

keyedfile.positionCursor(key,numberOfKeys)

but then i don't get the first record cause i use the method:

keyedfile.readNextEqual(key,numberOfKeys)

could someone please tell me how to get the records correctly?

i'm using jtopen 3.1 .

my code looks like this:

file.positionCursorBefore(key,numKeys);
while ((record = file.readNextEqual(key,numKeys)) != null)
{
        vector.addElement(record);
}

thanx in advance