I have used a modulus operator in a label class SQL query to label every fifth point in a point feature class in a map service. The feature class is in an SDE database running on SQL Server. The SQL i've used is PointNo % 5 = 0, and the labels show up just fine in the map service.
When storing the same featureclass in a file geodatabase, I use the expression mod(PointNo, 5) = 0. This works just fine in ArcMap but in the published map service, the point layer won't show up at all. I had to change the expression to Floor( PointNo/5)= PointNo/5 to make it work.
Is this behavior expected, or is it a bug? Shouldn't the modulus operators that work in ArcMap also work in a published map service? If not, it would be useful to get a warning when the map document is analyzed before publishing.