LTE cell should be added as external cell first using ADD GEXTLTECELL
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CellIdentity (CI) used to uniquely identify an LTE cell in the PLMN. For macro base stations, EUtran CellId consists of a 20-bit eNodeBID and an 8-bit CellID (EutranCellID = eNodeBID x 256 + CellID). For micro base stations, EUtranCellID is a 28-bit eNodeBID.
This is for Huawei.
Check this for other vendors too: