Notice: Undefined offset: 3 in line

I am a PHP newbie and I am getting two notices on a code that is part of a gallery, can you help me figure this out? Notices are

[CODE]Notice: Undefined offset: 3 in /home/raj/public_html/viewgallery.php on line 408
Notice: Undefined offset: 3 in /home/raj/public_html/viewgallery.php on line 426[/CODE]

Line 408 is

[CODE] ‘pcaption’ => $caption_array[$next]);[/CODE]

And line 426 is

[CODE]$result_final.= ‘<div class=”limage”><table><tr><td><table class=”image”><tr><td><a href=”photos/’.$cname.’/’.$caption_array[$next].’/’.$q.’/”><img src=”‘ . $images_dir . ‘/’ . $photo_filename . ‘” alt=” ‘ . $photo_keywords . ‘”></a><div class=”caption”>’ . $photo_caption . ‘</div><div class=”excerpt”>’ . $photo_description . ‘</div></td></tr></table></td></tr></table><div class=”underline”></div></div>’.$backString.'</div>’;
[/CODE]

The above lines are part of this code…

[CODE]
$next = 0;
$prev = 0;
if ($ct > 1)
{

$key = array_search($pcaption, $caption_array);
$prev = $key – 1;
if ($prev < 0) $prev = $ct – 1;
$next = $key + 1;
$searchNext = $key + 1;

if ($next == $ct) $next = 0;
$total_count = count($caption_array);
$result_final.= “<div id=’prevnext’>”;
$parameters_next = array(
‘cname’ => $cname,
‘pcaption’ => $caption_array[$next]
);
$parameters_prev = array(
‘cname’ => $cname,
‘pcaption’ => $caption_array[$prev]
);

$categoryNamePrev = $cname;
$photoCaptionNext = $caption_array[$next];
$photoCaptionPrev = $caption_array[$prev];

if($q !=” && $searchNext==$ct ) {

$previousUrl = ‘photos/’.$categoryNamePrev.’/’.$photoCaptionPrev.’/’.$q.’/’;
$nextUrl = ‘/searchmyway.php?q=’.$q.’&form_id%3Asearch=1′;
} else {

if($q != ”) {
$previousUrl = ‘photos/’.$categoryNamePrev.’/’.$photoCaptionPrev.’/’.$q.’/’;
$nextUrl = ‘photos/’.$categoryNamePrev.’/’.$photoCaptionNext.’/’.$q.’/’;
} else {
$previousUrl = ‘photos/’.$categoryNamePrev.’/’.$photoCaptionPrev.’/’;
$nextUrl = ‘photos/’.$categoryNamePrev.’/’.$photoCaptionNext.’/’;
}
}

$result_final.= ‘<span class=”prev”><a href=”‘.$previousUrl.'”><img src=”/photos/assets/left.png” alt=”left navigation”></a></span>’;
$result_final.= ‘<span class=”next”><a href=”‘.$nextUrl.'”><img src=”/photos/assets/right.png” alt=”right navigation”></a></span>’;
$result_final.= “</div>”;
}
}

$key = array_search($pcaption, $caption_array);
$prev = $key – 1;
if ($prev < 0) $prev = $ct – 1;
$next = $key + 1;
$searchNext = $key + 1;
$parameters_next = array(
‘cname’ => $cname,
‘pcaption’ => $caption_array[$next]
);
$parameters_prev = array(
‘cname’ => $cname,
‘pcaption’ => $caption_array[$prev]
);

if($q != ”) {
$backString = ‘<a href=”/searchmyway.php?q=’.$q.’&form_id%3Asearch=1″>Back</a>’;
} else {
$backString = ”;
}

if($q == ”) {
$result_final.= ‘<div class=”limage”><table><tr><td><table class=”image”><tr><td><a href=”photos/’.$cname.’/’.$caption_array[$next].’/”><img src=”‘ . $images_dir . ‘/’ . $photo_filename . ‘” alt=” ‘ . $photo_keywords . ‘”></a><div class=”caption”>’ . $photo_caption . ‘</div><div class=”excerpt”>’ . $photo_description . ‘</div></td></tr></table></td></tr></table><div class=”underline”></div></div>’.$backString.'</div>’;
} else {
$result_final.= ‘<div class=”limage”><table><tr><td><table class=”image”><tr><td><a href=”photos/’.$cname.’/’.$caption_array[$next].’/’.$q.’/”><img src=”‘ . $images_dir . ‘/’ . $photo_filename . ‘” alt=” ‘ . $photo_keywords . ‘”></a><div class=”caption”>’ . $photo_caption . ‘</div><div class=”excerpt”>’ . $photo_description . ‘</div></td></tr></table></td></tr></table><div class=”underline”></div></div>’.$backString.'</div>’;
}[/CODE]

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