PlaneId is different from created Datum Plane feature ID

Hi,

My requirement: Create a datum plane in assembly referring to a surface. Then use this datum to create a section in assembly.

I created datum plane by populating element tree.

wfcWFeature_ptr datumFeat= currSolid->WCreateFeature(elemTree, featOpts);

I get datum created correctly. Now I want to use this datum for creating section. so I query its ID by 

planeID = datumFeat->GetId();  //ID i got is 43

When I create a section by 

parentSOlid->CreatePlanarXSection(sectionName, planeId, cutObjtype, memberIdTable, quiltID, xtrue, compExcl);

system gives me error.

So I reselected the created datum and checked for its ID, it is 44. Now if I give this ID to above section function, it works well.

Am I missing something to differentiate between planeID and datum feature ID.