Autoresolve Using Unique ID

I am trying to link and then auto resolve an incident.
An initial email is sent to the service saying there is an issue. This email has an “Original Problem ID: 999999”
Once the issue has cleared a resolved email comes in that will also reference the “Original Problem ID: 999999”

It has to resolve using the unique problem ID.
I have tried with this regex statement - (^Original problem ID:+ \d*) and (^Original problem ID:+ \d{1,9}) and neither work.
I am at a loss.

I figured it out.
(Original problem ID: \d{6})