Hello there, after I printed out my return, I noticed that there is a Form 8453 that I need to mail in? For some reason, the box for the Form 8949 was checked. Is this the result of capital gains from sales of stocks/mutual funds? Is there anything I was supposed to check on Sch. D to get rid of Form 8453? I don't remember that I needed to file this Form 8453 in the past when I had capital gain? Thanks!