You don't say where you are entering this formula, nor which is sheet1 or sheet2, so I am confused.

This formula =IF(A3=MTrack!A$2:A$152,1,"") won't work because you have a range to compare A3 against and that won't work in this instance.

The formula I gave you, =IF(A1=Sheet1!$A$1,1,"") , will work if you modify the cell reference to meet your needs.

Try this in cell C2 on the MTrack sheet:

=IF(A2=Sheet1!$A$3,1,"")

Then copy this formula down column C to row 152. The rows on the MTrack sheet that have a match to Sheet1 A3 will show a '1', else will be blank.

HTH

Bruce