GROUP_CONCAT and Longtext

I need to concatenate two text fields in a MySQL database table in One, so I used the following SQL script to do it.

Table: tbl_newsitems Combine: need to concatenate text in "ni_text" with the same "news_id", Table layout:

Code used to combine text: SELECT    news_id

  GROUP_CONCAT ( ni_text

  SEPARATOR ') FROM tbl_newsitems GROUP BY news_id

;

But it will not display the full (complete) text in the results section. The CONCAT field is truncated and skips some text. The default data type for the CONCAT field is TEXT (1024)

Result:

So how do I combine all the text into one field without discarding the content. Please give me a script for this.

thank