Adding NEW sub domains to an existing Multisite installation

Hi there,
two weeks installed on dedicated server the wordpress MULTISITE (main website/domain) application as a larger WordPress Network installs using as well a multi-DB structure. Setting up the first two sub domains (coffeelovers.dealsm... + stationary.dealsm….) could be done without any problem and are working since properly.

Now, adding additional sub domains (e.g. testing.dealsm…, welcome.dealsm…) the new sub domains are setup successfully, see attached email confirmation as well as screen shots (accordingly named with 01dsmh, 02dsmh...).

Clicking the link to login an ERROR 500 occurs… (provider stated it’s not a server issue; dealsmarthosting,com is accessable).
Checking the NEW Site setting reveals the following situation:
- New site is NOT added to the database also
- ‘Multisite support is not enabled’ anymore
- BUT hovering over the listing reveals that new site is an EXTERNAL Domain!

Comparing site entries of e.g. http://coffeelovers.dealsm... With the newly entered site turns out the ‘http’ prefix is missing.
Editing SITE SETTINGS of ://bandon2.dealsm… to http://brandon2.dealsm.... does not accept ‘SAVE CHANGES’.

Now: How do I solve this issue? Provider does NOT not support wordpress + multisite + database issues.

Any help to solve this hassle is much appreciated.
Thanks + regards