Problem add Gateway Milesight

Problem add Gateway Milesight

Good afternoon, we are adding a milesight gateway and the following problem appears


An unexpected error occurred while trying to handle your request. Please
Please try the request again and contact your administrator if the problem persists.

Details error:

Unexpected exception: XML not
valid javaxxmlbind.UnmarshalException - with bound exception:
org xml.sax SAXParseException; line number: 1; column number:
1; Content is not allowed in the prologue.