No error detection scheme is perfect ?

No error detection scheme is perfect because transmission errors can affect data or additional information as well as the data'

In communications, error detection refers to a class of techniques for detecting garbled messages.

No any error detection scheme is completely perfect because transmission error can occur due to transmission impairments any time even though error detection scheme is using there. By using error detection scheme chance of errors occurring is reduced but cannot be completely removed.Error detection scheme minimizes the probability of passing incorrect frames to the destination.