four_button plugin, first/last images not unique

LesG

I'm using the four_button plugin and have it functioning fine. I've removed the text and attempted to replace the 4 images with custom buttons. The first and last buttons come across as the next and previous buttons. I've added this to my style page:

[code]
.paginate_enabled_first { background: url('/bia/apps/Global/Javascript/ext-3.2.1/resources/images/default/grid/page-first.gif') no-repeat top left; }
.paginate_disabled_first { background: url('/bia/apps/Global/Javascript/ext-3.2.1/resources/images/default/grid/page-first-disabled.gif') no-repeat top left; }

.paginate_enabled_previous { background: url('/bia/apps/Global/Javascript/ext-3.2.1/resources/images/default/grid/page-prev.gif') no-repeat top left; }
.paginate_disabled_previous { background: url('/bia/apps/Global/Javascript/ext-3.2.1/resources/images/default/grid/page-prev-disabled.gif') no-repeat top left; }

.paginate_enabled_next { background: url('/bia/apps/Global/Javascript/ext-3.2.1/resources/images/default/grid/page-next.gif') no-repeat top right; }
.paginate_disabled_next { background: url('/bia/apps/Global/Javascript/ext-3.2.1/resources/images/default/grid/page-next-disabled.gif') no-repeat top right; }

.paginate_enabled_last { background: url('/bia/apps/Global/Javascript/ext-3.2.1/resources/images/default/grid/page-last.gif') no-repeat top right; }
.paginate_disabled_last { background: url('/bia/apps/Global/Javascript/ext-3.2.1/resources/images/default/grid/page-last-disabled.gif') no-repeat top right; }

[/code]

What do I need to get my first/last buttons showing?
Thanks