sampler letters problem

[crpstx]

I finished my first filet crochet, a butterfly table doily, turned out great (if I do say so!). I've started a Bless This House sampler for a friend, and everything was great until I got to the letters. Is there some secret to having the lettering come out where they belomg? I do a 4 dc for my closed mesh, and ch 2 dc for the open but the letters are out of place. It is true if there are say 18 plain white squares, that means to crochet 18 open meshes?? I'm losing my nerve on this!! Please help! Thanks.