Alphabox Search Bug

I extended the Alpha Search to numbers as well. The row looks like that now:

'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z' ALL

instead of just letters we have numbers as well now and we could search also for 0. 1. 2. and so on in the DB.

Problem:
When I view members/items in lets say for example starting with "F", and I do a search on lets say for example names starting with "M" it would not show results even there are entries in the DB already starting with "M"
If I hit "ALL" the listview will reset and I can do a search for "M" again
Any ideas how to fix the alphabox search? I use this php code:
/**
* Returns a roman alphabet to select the first letters ot the title
*
* @access public
* @param current Alphachar
*/
function getAlphabox($alphachar,$joobase,$filter)
{
$alphabox = "<div style='width:auto;text-align:center;' class='pagination alphabox'>";
$alphabet= array ('0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z');
foreach ($alphabet as $achar) {
if ($achar==$alphachar) {
$alphabox .= "<span class='active'>".ucfirst($achar)."</span>";
} else {
$alphabox .= "<a href='".JoodbHelper::_findItem($joobase,"&filter=".$filter."&letter=".$achar)."'>".ucfirst($achar)."</a>";
}
}
$alphabox .= "<a href='".JoodbHelper::_findItem($joobase)."'>&raquo;".JText::_(' All')."</a></div>";
return $alphabox;
}


/**
* Returns Filter box for catalog view
*
* @access public
* @param current FilterSelect, Joobase, Searchstring
*/
function getFilterbox($filter,$joobase,$search,$letter)
{
$db =& JFactory::getDBO();

$filterform = "<form name='filterbox' method='post' action='".JoodbHelper::_findItem($joobase)."'><b>".$joobase->ffilter.": </b>"
."<select name='filter' style='width: 200px' >";

$queryfilter = "SELECT distinct(".$joobase->ffilter.") FROM ".$joobase->table." ";

if ($filter != '')
{
$queryfilter .= " WHERE ".$joobase->ffilter." != '".$filter."' ";
$filterform .= "<option value='".$filter."'>".$filter."</option>";
}

$filterform .= "<option value=''>...</option>";

$db->setQuery($queryfilter);
$result = $db->loadRowList();
foreach ($result as $fname)
{
$filterform .="<option value='".$fname[0]."'>".$fname[0]."</option>";
}

$filterform .="</select><input type='hidden' name='alphachar' value='".$letter."'><input type='hidden' name='search' value='".$search."'><input type='hidden' name='task' value='search'>&nbsp;<input class='button' type='submit' value='filter'></form>";

return $filterform;
}

PS: Forum cuts code to the right
'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u',
'v','w','x','y','z' ALL

would be the right line