Message property does not exist...

Check in the browser that the attribute name is correct. For attributes of list type (Fillets and Chamfers), check the indexes. The indexes specified must be consecutive  from 1 to n without any gaps.

The script below displays the message: "property does not exist: CstEdgeRibbon.2 on: EdgeFillet.1" at generation

Boite isa CATPart
{
boite isa Part
{
partbody isa BodyFeature
{
pad1 isa Pad
{
FirstLength = 0.5mm;
SecondLength=2.0mm;
}

fillet1 isa ConstantEdgeFillet ( "Face:(Brp:(pad1;2);None:())" )
{
CstEdgeRibbon.2\ Radius =1.0 mm;
}
}
}
}