[gradsusr] Back ground color problem

[AMS EmsiWx Bytča]

Dear Grads users,

I am facing problem with changing the background color:

function setmap(args)
'set mproj latlon'
*'set mpvals 5 30 40 58'
'set lon 10.05 24'
'set lat 45 54'
'set mpdset newmap'


'set rgb 250 0 136 162'
*'set display color white'
'set map 1 1 7'
'set background 250'


'c'
'set grid off'
'set grads off'


I have set the color n.250 , however using any number in 'set background 
250' except 1, I always get black background.

Am I doing something wrong?

Thank you for your time and help.


Marian