Albert Barnes Commentary Daniel 5:8

"Then came in all the king`s wise men; but they could not read the writing, nor make known to the king the interpretation." — Daniel 5:8 (ASV)

Then came in all the king’s wise men—the classes referred to previously, (Daniel 5:7).

But they could not read the writing—the script was an unknown script to them. It may have been a script which was not found in any language, and which made Daniel's power to read it the more remarkable, or it may have been, as suggested in the notes on Daniel 5:7, a foreign script with which they were unacquainted, though familiar to Daniel.