Reason is that there's no UCON register definition in the PIC18EXT.bas file

look at the end and add it like this
Code:
TXREG2	VAR	BYTE EXT
TXSTA	VAR	BYTE EXT
TXSTA1	VAR	BYTE EXT
TXSTA2	VAR	BYTE EXT
UCON    VAR	BYTE EXT <= here
VELRH	VAR	BYTE EXT
VELRL	VAR	BYTE EXT
WDTCON	VAR	BYTE EXT
WREG	VAR	BYTE EXT
hey!!! don't place the comment to the right