Through API I wanted to checkot the Cad Assembly from the WOrkspace and Checkin from the solidworks

I created one action in the windchill UI, if we click on that action it will collect all the cad Assemblies which is associated to WTPart from the structure and the collected cad assemblies  will be added to the workspace, from that workspace I wanted to checkout and  checkin the cad assemblies from the workspace.i am able to do checkout but checkin is not happening, its throwing error.

This is code that i written for the checkout and checkin.

private void checkoutAndCheckin(EPMDocument copy) throws WTException {
System.out.println("We are inside the Checkout and checkin method");

try {
wt.fc.ReferenceFactory referencefactory = new wt.fc.ReferenceFactory();
wt.fc.WTReference wtreference = referencefactory.getReference(copy);
wt.epm.EPMDocument epm = (wt.epm.EPMDocument) wtreference.getObject();
wtreference = referencefactory.getReference("OR:wt.epm.workspaces.EPMWorkspace:1150900");
wt.epm.workspaces.EPMWorkspace workspace = (wt.epm.workspaces.EPMWorkspace) wtreference.getObject();

// Get the EPMDocuments in the workspace
wt.fc.collections.WTSet hvm = wt.epm.workspaces.EPMWorkspaceHelper.manager.getObjectsInWorkspace(workspace, wt.epm.EPMDocument.class);

// Check out each EPMDocument
for (java.util.Iterator<?> iterator = hvm.persistableIterator(); iterator.hasNext();) {
wt.epm.EPMDocument epmDocument = (wt.epm.EPMDocument) iterator.next();
wt.fc.collections.WTArrayList partCollection = new wt.fc.collections.WTArrayList();
partCollection.add(epmDocument);
wt.fc.collections.WTValuedMap toCheckin = (wt.fc.collections.WTValuedMap) wt.epm.workspaces.EPMWorkspaceHelper.manager
.checkout(workspace, partCollection);

// Check in each EPMDocument
wt.fc.collections.WTKeyedMap checkinMap = new wt.fc.collections.WTKeyedHashMap(toCheckin.size());
for (java.util.Iterator<?> i_objects = toCheckin.persistableIterator(); i_objects.hasNext();) {
wt.vc.wip.Workable workable = (wt.vc.wip.Workable) i_objects.next();
checkinMap.put(workable, new wt.epm.workspaces.CheckinOption("Test checkin"));
}
wt.fc.collections.WTSet checkedInObjects = wt.epm.workspaces.EPMWorkspaceHelper.manager.checkin(workspace, checkinMap);
}

} catch (WTException e) {
e.printStackTrace();
}
}