Inserting 2D array into a SQL database

I have a standard php script inserting array values into a mysql database. One of my arrays is 2D, and when i try inserting values into it, what shows up in the database is array[1], array[2] etc, instead of the actual real values. Am i using the wrong insert parameters? Here's my sample code

Theres a for loop in the main body of my code(which is for a parser incidentally)

while (strpos($regionline, $c) == true)
{
$regionpos = strpos($regionline, $c);
$regionelement = substr ($regionline, $position, $regionpos);
$regionarray[$count][$regioncount] = $regionelement;
$regionline = substr($regionline, $regionpos+1);
$regioncount = $regioncount + 1;
}

And then outside of that there is a for loop, which runs through each element of one (shared) dimension of the array, and then a for loop inside that to exploit the 2D array. Here is my insert for the 2D array

for ($u=1;$u<$regioncount+1; $u++)
{
//echo $Physical_ISRC[$i]. ' ' .$regionarray[$i][$u];
//echo "<br>";

$sql = "INSERT INTO regionmeta Values ('$Physical_ISRC[$i]','$regionarray[$i][$u]');";
if (!mysql_query($sql,$connection))
{
die('Error: ' . mysql_error());
echo "$contentid[$i] not added";
}
else
{
echo "$i.$u done";
}

}

If i uncomment the echo statements at the start of the second quote, it displays properly the elements, and i've used that exact text for the insert statement, so that doesn't seem to be the problem. Does anybody have any ideas?