I wonder that what’s the problem of my code, anyonre can give a help??
Actually, I did once transaction before, however, I dont know why I cannot do it again
The error is like the figure below
In this project, I am dealing with generating slanted columns by using Revit API
Last part of my code about transaction as picture below.
trans = DB.Transaction(doc) trans.Start() nested_list_columns =  for list_line, list_column, list_level in zip(corresponding_line, corresponding_col_element, corresponding_level_element): temp =  for line, column, level in zip(list_line, list_column, list_level): temp.append(doc.Create.NewFamilyInstance(line,column,level, STR.StructuralType.Column)) nested_list_columns.append(temp) trans.Commit()
The input data of Create.NewFamilyInstance method are three nested list data, and I am sure that the data are definitely correct like the picture.