Alignment of fields in selection screen

Hi, i need some help with this.

I don't know why, but when i'm trying to put a parameter after a comment this strange spacement appears ( look attachment - line in blue ).

If i write the comment with numbers the aligment is normal.

Can somebody help me?

Obs: Sorry about my English, I'm a little busy here. =)

This is my code:

selection-screen begin of block b1a with frame title text-t01.

*-----------------Radio Buttons----------------------

selection-screen begin of line.

parameters: p_forn radiobutton group rad2 default 'X'.

selection-screen comment (50) rbtxt01.

selection-screen end of line.

selection-screen begin of line.

parameters: p_frete radiobutton group rad2.

selection-screen comment (51) rbtxt02.

selection-screen end of line.

selection-screen begin of line.

parameters: p_outros radiobutton group rad2.

selection-screen comment (75) rbtxt03.

parameters:p_dias(3) type n default 180.

selection-screen comment (75) rbtxt03b.

selection-screen end of line.

*-----------------Radio Buttons----------------------

parameters: p_consig as checkbox default 'X'.

selection-screen end of block b1a.