Data aren't inserting into database PHP - php

Question

I'm trying to add the data from my form into the database. But it's only refreshing. Here is my code for my form:
<form action="" method="post">
<div id="modal1" class="modal modal-fixed-footer">
<div class="modal-content">
<h4>Bedroom</h4><br><br>
<div class="row">
<div class="input-field col s6">
<i class="material-icons prefix">account_circle</i>
<input name="txt_room_ID" id="txt_room_ID" type="text" class="validate" readonly="true"
value="<?php
$sql= "select * from tblBedroom";
$stmt = sqlsrv_query($con,$sql);
while($rs = sqlsrv_fetch_array($stmt)){
$Setting_adminID = $rs['BedRoomID'];
$adminID_new = str_replace("B","",$Setting_adminID);
$adminID = str_pad($adminID_new + 1,11,0,STR_PAD_LEFT);}
echo htmlentities('B'. $adminID);
?>">
<label for="room_ID">Bedroom ID:</label>
</div>
<div class="input-field col s6">
<i class="material-icons prefix">account_circle</i>
<input name="txt_bedroom_no" id="txt_bedroom_no" type="text" class="validate">
<label for="bedroom_no">Room Number</label>
</div>
</div>
<div class="row">
<div class="input-field col s12">
<select name="txt_Room_Type">
<option value="" disabled selected>Choose Room Type</option>
<?php
$sql = "select * from tblBedRoomType";
$stmt = sqlsrv_query($con,$sql);
while($rs = sqlsrv_fetch_array($stmt)){
$BedroomTypeID = $rs['BedroomTypeID'];
$BedroomName = $rs['BedroomName'];
echo"<option value='$bedroomTypeID'>$BedroomName</option>";
}
?>
</select>
<label>Room Type</label>
</div>
</div>
</div><!--END OF MODAL CONTENT-->
<div class="modal-footer">
<a class="modal-action modal-close waves-effect waves-green btn-flat ">Cancel</a>
<input id="btn_Save" name="btn_Save" type="submit" value="Save" class="waves-effect waves-green btn-flat " onclick="return confirm('Are You Sure You Want To Save?');">
</div>
</div>
</form>
The php below the form:
<?php
if(isset($_POST['btn_Save'])){
$txt_room_ID = $_POST['txt_room_ID'];
$txt_bedroom_no = $_POST['txt_bedroom_no'];
$txt_Room_Type = $_POST['txt_Room_Type'];
$AcctStat = 1;
$sql = "insert into tblBedRoom (BedRoomID,BedroomType,RoomNo,AcctStat)
values('$txt_room_ID','$txt_Room_Type','$txt_bedroom_no','$AcctStat')";
$stmt = sqlsrv_query($con,$sql);
echo "<meta http-equiv='refresh' content='0'>";
}
?>
And my columns in my tblBedRoom are:
BedRoomID | BedroomType | RoomNo |AcctStat