Upload default image not being replaced

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PHP

Hi,
i have an upload feature and i wanted to set a default image if profile picture not uploaded

below code shows default image but when i upload the picture the default image stays there and doesnt replace it?

What I have tried:

$stmt = $conn->query("SELECT ProfilePicture FROM Profile WHERE UserID='$id'");
while($image =$stmt->fetch(PDO::FETCH_ASSOC)) {
if (!$_REQUEST['file']) {
echo "<img src=imgs/default.jpg width='150' height='150'/>";	
} else {
echo "<img src=uploads/".$image['Picture']."' width='150' height='150'/>"; 
}