can't change the size of the swap

[PostAdmin]

FreeBSD  5-2RELEASE 
The vinum volume manager.

I boot in single user mode

# mount -u /
# mount /usr
# bsdlabel ad0s1

=======================================================================
# /dev/ad0s1: 
8 partitions: 
#        size   offset    fstype   [fsize bsize bps/cpg] 
  a:  6291456   614400    4.2BSD     2048 16384 28552 
  b:   614400        0      swap 
  c: 78156162        0    unused        0     0         # "raw" part, don't edit 
  d:  1024000  6905856    4.2BSD     2048 16384 64008 
  e:  2097152  7929856    4.2BSD     2048 16384 28552 
  f: 68129154 10027008    4.2BSD     2048 16384 28544 
==================================================================

# bsdlabel -e ad0s1
===================================================================
# /dev/ad0s1: 
8 partitions: 
#        size   offset    fstype   [fsize bsize bps/cpg] 
  a:  6291456   614400    4.2BSD     2048 16384 28552 
  b:   614119           281      swap                                     #change
  c: 78156162        0    unused        0     0         # "raw" part, don't edit 
  d:  1024000  6905856    4.2BSD     2048 16384 64008 
  e:  2097152  7929856    4.2BSD     2048 16384 28552 
  f: 68129154 10027008    4.2BSD     2048 16384 28544 
=======================================================================
:wq

# bsdlabel  ad0s1
==================================================================
# /dev/ad0s1: 
8 partitions: 
#        size   offset    fstype   [fsize bsize bps/cpg] 
  a:  6291456   614400    4.2BSD     2048 16384 28552 
  b:   614400        0      swap 
  c: 78156162        0    unused        0     0         # "raw" part, don't edit 
  d:  1024000  6905856    4.2BSD     2048 16384 64008 
  e:  2097152  7929856    4.2BSD     2048 16384 28552 
  f: 68129154 10027008    4.2BSD     2048 16384 28544 
==================================================================

Can't change the size of the swap. In what a problem?