CIAA is established as constitutional organ to check corruption but corruption is still increasing day by day instead of decreasing. Why?

They have no power to took down the one that truly responsible

Explanation:

The corruption that occurs often time involved very powerful people on the upper echelon of the government seat.

The CIAA can only handle the people on the lower level. Their investigations tend to be stopped/blocked every time they got near the criminals on the upper level.