php：file_put_contents错误

I'm using file put content to save my image to the server, but I get an error and the image is not saved .

I am getting the base64 string from android app, I decode it and pass it on for saving. My php script is in this location (example):

www.aaa.com/test

I want to save the photos to:

www.aaa.com/test/photos

What I have:

$name = "image123.png";
$data = base64_decode($fldPostPhoto);
file_put_contents("photos/".$name,$data);