I'm trying to do some artwork for a large sign. I have set the page units to centimetres (cm) and have tried to set the size to 297cm x 95cm. But I get the warning message that the page width is invalid. It tells me that it must be a positive non-zero measurement, and that the maximum for page and margins is about 9ft (2.75M).

So I tried setting it to 275cm, same message. Tried changing the units to metres and entered 2.75 x .95. Same warning. I even tried rounding up to 1m as .95 is presumably not a positive non-zero measurement but it makes no difference.

Am I being really thick here?