Transmission shifting in overdrive

my ford escort 1993 goes into first and drive gear but will not go in to overdrive

Is the transmission fluid at the right level? Is the color good (pink and clear)? Has the transmission been serviced properly?

THIRD POST - SAME QUESTION - MORE INFO- WHICH TRANSMISSION ? AUTO ? MAN. ?

yes it is a aotomatic,thank you for your reply

An automatic could have several possible reasons for this . Cheapest first stab at it is to change the fluid and filter and chech the alignment of the shift cable to see that it is positioning the shift lever correctly. If these don’t work the problem’s inside . The valve body has both electric solenoids and mechanical valves and would need to be seen by a transmission shop to dignose and repair.