Ok, so i've searched and i've tried just about every recommendation out there in the forums. I finally got a KA mixer and since then, my bc icing has been gritty. I've tried both all shortening icing as well as butter/shortening combo. I haven't changed ps brands. What am i doing wrong? I have been beating the butter/shortening on speed 2, adding flavorings and then 1c ps at a time, scraping down teh sides. Am I supposed to beat the icing for a longer period of time? pls help.

Your fats may be too cold, try beating longer, or starting with softer butter, or warming it up a little by wrapping a hot, wet towel around the bowl briefly.
Or you may need to add a tiny amount at a time of liquid or egg whites.

The longer you beat the icing, the lighter, fluffier and smoother the texture will be. Don't whip it at too high a speed or you will create air bubbles (another issue all by itself). Try beating the icing on about 3 or 4 for 5 or more minutes. Also, as originalsugarchef said, be sure your fats are at room temp before you begin.

HTH

Yes, my fats are definitely room temp. so, should i whip it at speed 6? also, i've already made 4 batches of icing. is there any way i can fix it? or, do i need to throw it all out and start all over.