str_replace number shenanigans

str_replace number shenanigans

Alright, I'm currently stumped by this.
I have this code:
ECHO $CHECKVOTINGROW[VOTECHOICES];
ECHO $STRREPLACECHECKVOTECHOICES =
STR_REPLACE("U","",$CHECKVOTINGROW[VOTECHOICES])
output UUUSSS1
So the string replace of U's in UUUSSS is returning 1 instead of SSS.
What silly thing am I missing with this?
Edit:
$CHECKVOTINGROW[VOTECHOICES] ORIGINAL VALUE IS UUUSSS
I flagged this for removal, thanks for helping. Must be a problem
somewhere else causing problems. I won't subject people to more code for
parsing. Thanks again.