Yes, it's wrong.
Originally Posted by omid_61
Having seen your letter in my mailbox, I was both glad and sad.
Seeing your letter in my mailbox made me both glad and sad.
"Having seen" desribes a person, so you need a noun to tell us who that person is.
Having seen your letter, I was both glad and sad. = I saw your letter and I was glad and sad.
Having decided on a plan, the team quickly implemented it. = The team decided on a plan and the team implemented it quickly.
Having opened the box of cookies, Joe was unable to keep from eating all of them. = Joe opened the box and Joe ate them all.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.