Why does my forehand topspin has sidespin?

Hi coaches I have a really serious problem here for my forehand topspin.I know by right the forehand loop should create straight topspin to the ball.However my forehand topspin contains sidespin and I don't really know how to create the grazing motion onto the ball to have straight spin and sometimes my contact point is flat and erratic causing my forehand loop to be poor.Is there any causes for these mistakes?Help is really much appreciated as I been trying to correcting myself but to no avail for these mistakes.Thanks a lot

Hi Yong,

This usually happens when you drop your wrist on contact.  Try keeping the end of your bat up higher on contact.  Think a lot about the angle your bat is in on the actual contact point.  Sometimes when we start the swing the angle will be correct but at the point of impact we change the angle.

Yu may try to get a video f your stroke even if it is on your phone and take a look at it. It may solve some problems for you.