What would cause the vehicle to shut down? on 2003 Ford Expedition

"Check charging system" light keeps flashing and beeping. The altinator and batery have both been replaced within the last few days. What else would cause this vehicle to shut down

Closley inspect connectors at alt!!! All connectors at alt. Hook DVOM to batt. & watch voltage.
1 more answer , 1 more comment
Most probably your alternator is not charging the battery, you battery is drained.
Remember, both,the altinator are brand new,less than 14 days old. There are two different altinators for this truck. We made sure we that
We had the one. Could there possibly be anything else?