Justification in OpenXML

Hi Guys,
I am trying to create a word document using openxml sdk 2.0 Prodductive tool. While adding paragraph properrties if the justification is both(ie justified), i encounter a problem....,,, the line streaches to the entire width of the page to fill that perticular line some some thing like this..
Write                       a                               New                           Post. where as it is supposed to be just
Write a New Post. This is the case specially if its the paragraph's last line..
To put it in one line " the pharse / the string is streac ...