either you have a broken track, damaged solder through (make sure you solder the chip on the top tracks and bottom) or the chip has been damaged due to over heating when soldered.
when ever you replace an I.C. you should socket it.
you will need to take the board out of the machine and use a multi meter to beep out all the traces from every pin on the I.C. that you have installed to what ever component the trace goes to. (most of the traces from pins 1 to 9 go to U14 and most of the traces from pins 10 to 18 go to bottom of the resistors below U20)
