Its impossible to inherit templates with name not in lower case.

In acp_styles.php on line 3205:

		if (isset($cfg_data['inherit_from']) && $cfg_data['inherit_from'])

		{

			$sql = "SELECT {$mode}_id, {$mode}_name, {$mode}_path, {$mode}_storedb

				FROM $sql_from

				WHERE {$mode}_name = '" . $db->sql_escape(strtolower($cfg_data['inherit_from'])) . "'

					AND {$mode}_inherits_id = 0";

			$result = $db->sql_query($sql);

There is strtolower in sql query, which causes the problem.

Example:
I have style AcidTech installed, with all its components.
In template.cfg for AcidTech Test I have this code:

inherit_from = AcidTech

Check in acp_styles.php tries to find template "acidtech" instead of "AcidTech" because of that strtolower and shows error that "acidtech" doesn't exist.