Erro substring sql

SELECT
    NI.CHV_NFE,
    NI.COD_ITEM,
    PROD.NCM_PRODUTO,
    NI.DESCR_COMPL,
    NI.QTD,
    NI.UNID,
    NI.VL_ITEM,
    NI.VL_DESC,
    NI.CST_ICMS,
    SUBSTRING(CST_ICMS_TABA.CST_ICMS FROM 1 FOR 1) AS  CST_ICMS_I,
    SUBSTRING(CST_ICMS_TABA.CST_ICMS FROM 2 FOR 3) AS CST_ICMS_II,
    NI.CFOP,
    NI.ALIQ_ICMS,
    NI.VL_ICMS,
    CFOP.CFNOME,
    CST_ICMS_TABA.DESC_CST,
    CST_ICMS_TABB.DESC_CST
FROM NFE_ITEM  NI, PRODUTO PROD, CFOP, CST_ICMS_TABA, CST_ICMS_TABB
WHERE NI.COD_ITEM = PROD.COD_PRODUTO AND
NI.CFOP = CFOP.CFOP AND
CST_ICMS_TABA.COD_CST = CST_ICMS_I AND
CST_ICMS_TABB.COD_CST =CST_ICMS_II