Daniel 5:8,9

‘Then all the king's wise men came in. But they could not read the writing or make its interpretation clear to the king. Then was king Belshazzar greatly troubled, and his face was changed on him, and his lords were perplexed.'

None of the wise men of Babylon were able to read and decipher the writing. Whether this means that the script was unintelligible, or just that its meaning was difficult, does not really matter, although the former is probable as they could at least have made a guess at the latter. The result was that the king, who had had time to recover himself, once again went into a blue funk, although not quite so badly as before. His lords also did not know what to think or say. All knew that it spelt something ominous.