Sql error

I get error . When I try to query this one :

select txn_year,txn_month, sum(transaction_volume) as transaction_volume from (select year(from_unixtime(t.timestamp/1000)) as txn_year,MONTHNAME(from_unixtime(t.timestamp/1000)) as txn_month, count(t.id) transaction_volume from type_4 t where t.assetId="EvN8cvuGKC2t1PA8ZEsgJth3paenSP4UAd8Z6K14z2P4" GROUP BY txn_month,txn_year union select year(from_unixtime(t.timestamp/1000)) as txn_year,MONTHNAME(from_unixtime(t.timestamp/1000)) as txn_month, count(t.id) transaction_volume from type_11 t where t.assetId="EvN8cvuGKC2t1PA8ZEsgJth3paenSP4UAd8Z6K14z2P4" GROUP BY txn_month,txn_year ) sd GROUP BY txn_month,txn_year ORDER BY FIELD(txn_month,'January','February','March','April','May','June','July','August','September','October','November','December');