I have a problem...need help

I load at rin time a KbmMemTAble with no field from a query

MTPersonal->Close();
MTPersonal->LoadFromDataSet(DM->qSelect,TkbmMemTableCopyTableOptions
() << mtcpoStructure << mtcpoProperties << mtcpoLookup <<
mtcpoCalculated << mtcpoFieldIndex);
MTPersonal->Open();


In that moment, i want to add new field to MTPersonal like
MTPersonal->FieldDefs->Add("TEST", ftString, 20 , true);


okkk...work but when i want to use the TEST field...MTPersonal->Locate
("TEST","1",Opts)

ERROR!! TEST field does not exist????

Please give advice how to add fields at run time, after
LoadFromDataSet