Some KEGG IDs cannot be found in the database

[cailing20]

I can find them in KEGG (WebDBGET Entry Retrieval Failed) but not in MetaboAnalyst ID conversion tool
C03212
C00586
C02040
C06414
C21031
C01017
C19851
C02290
C13050
C01420
C02872
C00661
C03947
C20793
C03953
C04423
C01742
C02057
C16435
C06468
C06746
C12064
C03537
C03727
C02886
C03030

[jeff.xia]

This is a common question. Please read this post