Ask the gods to see why my $act received a value of delmes but cannot execute the statement after ElseIf

Ask the gods to see why my $act value is delmes but cannot execute the statement after ElseIf?
$act =$_request[' act '];
$username =$_request[' username '];
$title =$_request[' title ';
$content =$_request[' content ';
$profile =$_request[' profile ';
$ip =$_server[' remote_addr '];
$date =date ("y-m-d h:i:s", Time ());
$id =$_request[' id '];
Echo $act, $id;

if ($act = = "Doaction") {
$filename = "Messages.txt";
if (file_exists ($filename)) {
$str =file_get_contents ("Messages.txt");
$array =unserialize ($STR);
}
$array []=compact ("username", "title", "title", "Content", "Profile", "IP", "date");
File_put_contents ("Messages.txt", Serialize ($array));
}
ElseIf ($act = = "Delmes") {
echo "1111";
}
------to solve the idea----------------------
What is the output of the page?

You'd better var_du,p ($_request); Take a look at what's actually passing in.
------to solve the idea----------------------
Var_dump ($act); Let's see what the value is.

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