tie across measure line

I've got several notes with values that involve crossing measure lines. No matter what I do, when I get to the new measure the note plays again rather than being held as a continuous value. For example, I have a quarter note (D) that needs to be written out as 1/8 note at the end of one measure and another at the start of the subsequent measure. It looks right, ties and all, but when I run the playback each 1/8 note gets its own strike. I've already tried the recommendations from the instruction book,