Try using a variable for the starting column and BAR width.
Code:
COL  VAR BYTE
Width VAR BYTE

lcd_main:
Lcdout $fe, 1 
LCDOUT "Forw: ",dec4 fwd_pwr," Watt"
pause 10
COL = 16 : Width = 25
; syntax- BARgraph   Value,    Row,  Col,  Width, Range, Style
 @         BARgraph  _fwd_pwr,   1, _COL,_Width,   1024,  boxed  ' OK
; @         BARgraph  _fwd_pwr,   1,   16,    25,   1024,  boxed ' not OK  
return
The routines use a "trick" method to determine if the parameters being passed are constants or variables.

Anything less than 16 is assumed to be a constant, and anything over that is taken to be the address of a variable.
If it went up to 40, it could mistake a variable as a constant.

On anything wider than 16 chars, you should use a variable for Col and Width.

hth,