Service Unit Count
This rejection is stating that a charge was billed and had a value of '0' entered for units. A unit count of 1 or higher must be used for purposes of claims, as there is no way to bill zero units.
Open up the selected charge(s) for the claim that was rejected and find the charge that has a '0' entered in the 'Units' field. It may also be necessary to update the fee schedule via the References Ability to ensure the '0' does not continue to pull to the claim. The claim can then be rebuilt and resent.