Not sure where you got that info, astrodog, but I'm afraid it's wrong. The Beatles version of Yesterday was not released as a single in the UK until 1976, when it reached number 8. The highest charting version in the UK was actually by Wet Wet Wet (would you believe?) who reached number 4 in 1997.
I think PatTheRat may have solved the riddle. There was a point during the 60s when it was decided to exclude EPs from the singles chart. Certainly the 1976 single release is the only mention of it in the Guinness Book of British Hit Singles.