# Region file format: CIAO version 1.0	
-rotbox(4055.375,4165.5674,4.6747966,4.4715447,63.400002)
annulus(4059.5601,4163.4399,2.0325203,7.113821)

Since the software processes the shapes in their listed order, CIAO attempts to exclude this shape from an area that has not yet been defined. The field() region, which defines the entire field of view, can be added to the beginning of the region file to avoid syntax errors:

# Region file format: CIAO version 1.0
field()
-rotbox(4055.375,4165.5674,4.6747966,4.4715447,63.400002)
annulus(4059.5601,4163.4399,2.0325203,7.113821)

Note that the order of the regions does matter; if you intend for the box to be excluded from the annulus:

# Region file format: CIAO version 1.0
field()
annulus(4059.5601,4163.4399,2.0325203,7.113821)
-rotbox(4055.375,4165.5674,4.6747966,4.4715447,63.400002)

See the Using CIAO Region Files thread and ahelp dmregions for more information.