I have reviewed your code. There are only two mistakes for which the support reaction values are extract as zero. You have incorrectly used the variable names during specifying the variable type. You have used the following function--
objOpenSTAAD.Output.GetSupportReactions NodeA, loadcase, dReactionArray
The variable types are defined as--
loadcas As Integer
Dim NodesA As Long
As the variable types for NodeA and loadcase (used in the function) are not specified in your code, the support reactions values are extracted incorrectly. You need to modify the variable names as --
Dim loadcase As Long
Dim NodeA As Long
After this change, you will find that correct reaction values are extracted.