loop at screen

hi friends,

i need small help.

i hav the requirement:

if the chkbox p_chk is checked, (p_chk = 'x').

then make the parameter mandatory. (screen-required = 'x').

if the chkbox p_chk is not checked, (p_chk = '').

then make the parameter is not mandatory. (screen-required = '').

in this case, the 2nd option is not working.

i.e., screen-required = ''.

what should be the parameter i should use here and the value to be passed to that.

could you all please look into this and suggest me some solution.

Thanks,

Praveen