The First question to look into before examining the code:
You have the UE behavior set to redirect to the aanmeldentks.php after sending the email, does this redirect occur?
One issue i see strait away is that both the from address and the to address are the same. Many SMTP Servers will not relay the email if the from and to address are the same since this is a common practice used in spam emails. You should make sure to use a unique email for the from address and the to address.
Who is your host? you have not entered an SMTP server address or port. This may work on some hosts, but may not on others.
in the email body section of the waue_sollform_1.php file, it is set to get the email body from the aanmelden_WAUE_HTML_WA_Universal_Email_1.php:
$MailBody = $MailBody . (GetFromPage("../../aanmelden_WAUE_HTML_WA_Universal_Email_1.php"));
this is a temp file created by UE, and should not be used for the email template.
you should select to use one of the em,ail templates and not chose the UE temp file.