Access: Adding 1 to a null value

I have a calculated field that, because it is then used as a divisor, may not be a null value. (I also do not want the record left out of the calculation!)I'm trying to add 1 to the value so that I never have a null value but Access is ignoreing me.

This is the SQL:
PARAMETERS RecordDate DateTime;
SELECT LaserActiveSystems.SerialNo, [RecordDate]-[LaserActiveSystems]![InstallationDate] AS DSI, mscqrySurveyServiceLaser.Distributor, mscqrySurveyServiceLaser.Region, dbo_stdModelNumber.ModelGroup, [DSI]/[RepairsCount] AS MTBSC, [LaserActiveSystems]![InstallationDate] AS InstallationDate, 1+[mscqrySurveyServiceLaser-RepairCount]![RepairCount] AS RepairsCount
FROM ((dbo_stdModelNumber INNER JOIN LaserActiveSystems ON dbo_stdModelNumber.ModelNumber = LaserActiveSystems.ModelNumber) LEFT JOIN mscqrySurveyServiceLaser ON LaserActiveSystems.SerialNo = mscqrySurveyServiceLaser.SerialNo) LEFT JOIN [mscqrySurveyServiceLaser-RepairCount] ON LaserActiveSystems.SerialNo = [mscqrySurveyServiceLaser-RepairCount].SerialNo
WHERE (((mscqrySurveyServiceLaser.RecordDeleted)=False) AND ((mscqrySurveyServiceLaser.ServiceDate)<[RecordDate] And (mscqrySurveyServiceLaser.ServiceDate)>=[LaserActiveSystems]![InstallationDate]) AND ((mscqrySurveyServiceLaser.OutOfServiceDate) Is Null Or (mscqrySurveyServiceLaser.OutOfServiceDate)>=[RecordDate]))
GROUP BY LaserActiveSystems.SerialNo, mscqrySurveyServiceLaser.Distributor, mscqrySurveyServiceLaser.Region, dbo_stdModelNumber.ModelGroup, [LaserActiveSystems]![InstallationDate];
1+[mscqrySurveyServiceLaser-RepairCount]![RepairCount] AS RepairsCount 1+[mscqrySurveyServiceLaser-RepairCount]![RepairCount] AS RepairsCount 1+[mscqrySurveyServiceLaser-RepairCount]![RepairCount] AS RepairsCount