The forum software requires a unique user display name when registering or requesting a user display name change.
on ubbcentral.com there is only user with the display name of "peter" but there is a "peterhd" and "peter2x3" and "peter poll"
when you are asked to type a display name of the member you want to send a private message to, and you type "peter" in the display name box, "peter" is the user which is verified that exists, and is added.
this works just like your email program. you are expected to know which member display name you want to mail to, as you are typing their display name.
there is also a drop-down selector where you can choose a member from your "friend list." this is the list of users you've added and crested yourself. it works just like an address book, but keeps track of your forum "friends" even after they change their display name.
could the feature be made in to an Ajax style lookup where a list of the top 15 "peter" results are presented as you type each letter? sure, but then you'd still have to guess at which of the (on ubbcentral.com) OVER 100 display names within that list with some variation of "peter" for the display name.
the best solutions are to either
a) know the exact display name you want to send your private message to
or
b) select to send the private message to the member from their member profile page using the user list search tool.
or
c) have the user which you commonly send private messages to on your friend list
or
d) select to send a private message to the member by choosing "send private message" from the name drop down menu of the author content section on one of their posts.
ubb.threads forum software is setup to require all members to have a unique display name. if you have over 200 variations of a user display name, then that's what you have.
UBBCentral has this, probably because it is dealing with a list of users dating near 20 years, and a portion of those were crested as test accounts or spammers or whatever.
"peter" is a very common name, but there is only one unique "peter" on
UBBCentral. if you choose that as the one you are are sending to when asked which user to send to, that the one you will be sending to. the display name box is not a lookup, it is a case-insensitive matching field entry box.