Setting Y values...help!

In my MC i have 12 pictures going vertically …and i’m almost done! i’ve got to calculate every position by entering a # for y values. I entered 6400 for Y value…and i get an error message that reads “invalid position & value” …
Ughhhhhh. iT WORKED yesterday…it does this sometimes…anyone know what i can do?

thx Cristina:book: