How do I increase the length in data file

Question

I have been getting this error, can anyone tell me why I'm getting the error below and help me fix the the error( increase the length of data file.
This is my Control file
LOAD DATA
INFILE Job.dat
APPEND INTO TABLE job
FIELDS TERMINATED BY x'09'
(PositionID, jobID, title, code, family)
This is my data in my data file
PositionID JobID Title Code family
50003490 1 NULL 001610 NULL
50004865 1 NULL 001615 NULL
ERROR
SQL*Loader: Release 10.2.0.1.0 - Production on Fri Jul 13 10:17:33 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Control File: Position1.ctl
Data File: Job.dat
Bad File: Job.bad
Discard File: none specified
(Allow all discards)
Number to load: ALL
Number to skip: 0
Errors allowed: 50
Bind array: 64 rows, maximum of 256000 bytes
Continuation: none specified
Path used: Conventional
Table JOB, loaded from every logical record.
Insert option in effect for this table: APPEND
Column Name Position Len Term Encl Datatype
POSITIONID FIRST * WHT CHARACTER
JOBID NEXT * WHT CHARACTER
TITLE NEXT * WHT CHARACTER
CODE NEXT * WHT CHARACTER
FAMILY NEXT * WHT CHARACTER
Record 1: Rejected - Error on table JOB, column POSITIONID.
Field in data file exceeds maximum length
Record 2: Rejected - Error on table JOB, column POSITIONID.
Field in data file exceeds maximum length
Record 3: Rejected - Error on table JOB, column POSITIONID.
Field in data file exceeds maximum length
Record 4: Rejected - Error on table JOB, column POSITIONID.

Answer 1

this is the structure of my table
create table job (PositionID number(20) not null,
jobID number(20) not null, title nvarchar2(255), code nvarchar2(255), family nvarchar2(255),
constraint job primary key (PositionID, jobID))
organization index
Tablespace Position
pctthreshold 20
overflow tablespace users;
comment on table job is 'This table defines the job(s) associated with the position. There can be multiple jobs allowed although the preferred business rule is for one job per position.';
alter table job add constraint FKjob373174 foreign key (PositionID) references Position;