Daniel 5:8

Overview - Daniel 5
Belshazzar's impious feast.
A hand-writing unknown to the magicians, troubles the king.
10 At the commendation of the queen Daniel is brought.
17 He, reproving the king of pride and idolatry,
25 reads and interprets the writing.
30 The monarchy is translated to the Medes.
Treasury of Scripture Knowledge

Daniel 5:8  (King James Version)
Then came in all the king's wise men: but they could not read the writing, nor make known to the king the interpretation thereof.

Because, probably, it was written in the ancient Hebrew or Samaritan character.
2:27 4:7 Genesis 41:8 ; Isaiah 47:9 Isaiah 47:12-15