Google Sheets Script - Not Recognizing Sheet - google-apps-script

Question

I've a Google Sheet.
I went to Tools > Script Editor.
I want to send an email when there are new rows in the sheet.
Here is my script below.
When debugging the ss variable seems to be set but is null.
So when I get to getSheetByName it is also null.
I'm not sure why it isn't getting the sheet.
// This constant is written in column C for rows for which an email
// has been sent successfully.
var EMAIL_SENT = 'EMAIL_SENT';
/**
* Sends non-duplicate emails with data from the current spreadsheet.
*/
function sendEmails() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getSheetByName('Pricing Changes');
var startRow = 2; // First row of data to process
var numRows = 0; // Number of rows to process
numrows = sheet.getLastRow();
// Fetch the range of cells A2:B3
var dataRange = sheet.getRange(startRow, 1, numRows, 3);
// Fetch values for each row in the Range.
var data = dataRange.getValues();
for (var i = 0; i < data.length; ++i) {
var row = data[i];
var vdate = row[0]; // First column
var vasin = row[1]; // Second column
var vcurrentprice = row[2]; // Third column
var vnewprice = row[3]; // Third column
var vremarks = row[4]; // Third column
var emailsent = row[5]; // Third column
var message = vdate & "-" & vasin & "-" & vcurrentprice & "-" & vnewprice & "-" & vremarks;
if (emailSent !== EMAIL_SENT) { // Prevents sending duplicates
var subject = 'Sending emails from a Spreadsheet';
MailApp.sendEmail(emailAddress, "New Price Changes", message);
sheet.getRange(startRow + i, 3).setValue(EMAIL_SENT);
// Make sure the cell is updated right away in case the script is interrupted
SpreadsheetApp.flush();
}
}
}
Note that I have set it up as a File as it was previously set up as "Code" but I thought perhaps that was the issue. (I'm not able to embed the image so hopefully stack will put the correct image link.)
App Script UI Screen Shot

Answer 1

Since you mentioned that both getActive() and getActiveSpreadsheet() returns a null. The last option you have to get the Spreadsheet object is to use either of the following:
1. openById(id)
Opens the spreadsheet with the given ID
A spreadsheet ID can be extracted from its URL. For example, the spreadsheet ID in the URL https://docs.google.com/spreadsheets/d/abc1234567/edit#gid=0 is "abc1234567".
2. openByUrl(url)
Opens the spreadsheet with the given URL. Throws a scripting exception if the URL does not exist or the user does not have permission to access it.