When creating a shipping rule with multiple conditions specified, for an order to match this rule it must match both of the specified conditions.
For example, the following rule is for DPD Parcel Next Day:
For an order to match this rule, it must match all of the following conditions, so only orders with a value of over £30, with a shipping method of "fast track" being sent within Great Britain will match this rule, even an order that matches one or two of the conditions will either match a different rule or be set as ignored.
However, if you wanted your shipments to be sent with this service on any of these conditions rather than only on all three, you can do this by creating a rule for each condition, as shown here:
This would mean that if a shipment matches any of the three conditions, it will be sent with DPD Parcel Next Day.
If you have any questions, or would like any help getting set up, please contact support.