I'd try UtoA only on the user name, not the entire command line.
 Code:
$UserName = UtoA($UserName)
I'm not positive that it will solve your issue, but it's a good try. Display the results of the $UserName before/after the conversion to see if it helps.

Also, here's an alternative to remove "LDAP://" from a string
 Code:
$UserOU = Join(Split($UserOU, 'LDAP://'), '')
This splits the string into an array using "LDAP://" as a delimiter. The array is joined into a string, using nothing as a delimiter. The result is that the original delimiter is removed from the string. Shane's example also works, but only for this specific example (one instance of the removed text at the beginning of the string).

I'll take a look at the special char issue and see if it's really a Unicode/ASCII issue.

Glenn
_________________________
Actually I am a Rocket Scientist! \:D