How to fetching users to people picker that time remove error message("No exact match was found")

hi

fetching users to people picker (multi users).that time i got  message "No exact match was found. Click the item(s) that did not resolve for more options."

but when i click an Check name it will remove..this message will display when binding time to people picker control..[ if fetch single user it will not display this message.this message will display only above 1 users]

EX: user1;user2;