This can happen only if the the paper sensor in the tray is malfunctioning or has dirt over it. You need to remove the paper tray and clean it with compressed air and also clean the printer internally and see result.
If problem persists you will need to get the printer repaired to replace the sensor. If in warranty send it to Brother or else take it to a local repair store. But it will be cheaper to buy a new printer if its out of warranty.
Try to do this too :
Remove all ink cartridges. Turn off printer, then turn it upside down and shake it few times.
Then put it in right position, turn it on and see if you find some change
Open up the printer and blow air in it (using compressed air can) to remove all dust.
Try to rub the paper feed rollers with some rough moist cloth to increase its traction (grip).
Feel free to ask any question or concern you may have. I will be glad to help you.
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