How to increment integer property in workflow script

I have an integer property that i need to increment in one of the workflow state actions.

I am using the following script which causes the error  "Object doesn't support this property or method"

Dim oProperty : Set oProperty = CreateObject("MFilesAPI.PropertyValue")
oProperty.PropertyDef = totalFailureId
oProperty.TypedValue.SetValue MFDatatypeInteger, 1

Dim a:a = Vault.ObjectPropertyOperations.SetProperty(ObjVer,oProperty)