mysqli bind_param类型中的元素数与绑定变量不匹配

Question

I have this query:

qry=INSERT INTO assessments (Speaking_and_listening, Reading, Writing, Number, Measure, Geometry, Statistics, Science, ICT, Health_and_well_being, Relationships, Living_in_the_wider_world ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)

I ceated two variables and a loop to do the binding:

foreach ($subjectListArray as $key=>$subject){
$sss .='s'; 
if (!isset($_POST[str_replace(" ","_",$subject)])){
    $fieldNameValues.='fred';   
}else{
    $fieldNameValues.=$_POST[str_replace(" ","_",$subject)];
}
if ($key!=(count($subjectListArray)-1)){
    $sss.=' ,';
    $fieldNameValues.=', ';
}
}

When I print out the two arrays $sss and $fieldNameValues I get this:

s ,s ,s ,s ,s ,s ,s ,s ,s ,s ,s ,s
p2iic, fred, fred, fred, fred, fred, fred, fred, fred, fred, fred, fred

Which looks right to me.

However when prepare and bind thus:

$record= $conn->prepare($qry);  
$record-> bind_param($sss, $fieldNameValues);

I get errors telling me

Warning: mysqli_stmt::bind_param(): Number of elements in type definition string doesn't match number of bind variables

which as far as I can see it does - there are 12 in the $ary, and twelve in $sss and 12 in $fieldNamesValues

What's wrong please?