How to change a Composition LifeCycle to Archive?

While on the Compliance tab for a Manufacturer Part, I can archive a composition by clicking on the <Archive> button at the bottom of the screen. When I tried to simulate such action from a Java PX using the code below, and received an error indicating the attribute is read only. Can someone tell me how I can achieve what I need?

ITable declaTable = mpnPart.getTable(ManufacturerPartConstants.TABLE_COMPOSITIONS);

Iterator declaIter = declaTable.iterator();

// while loop to get the matching row

while (declaIter.hasNext()) {

                                                                                             

                IRow declaRow = (IRow)declaIter.next();

                String declaSpName = declaRow.getValue

                                (ManufacturerPartConstants.ATT_COMPOSITIONS_SPECIFICATION).toString();

                if(declaSpName.equalsIgnoreCase("Generates Hazardous Waste")){