table of content file link not add in toc.ncx file

[bhambhu]

Hi,
i m convert docx file to epub.
after convert file i see file structure. table of content file link missing in in toc.ncx file.
table of content file name index_split_001.html but its not in toc file

my toc.ncx file code

<navMap>
<navPoint class="chapter" id="num_1" playOrder="1">
<navLabel>
<text>1. Mickey Mouse Is Watching You: Does Disney's MyMagic Know Too Much?</text>
</navLabel>
<content src="index_split_002.html"/>
</navPoint>
<navPoint class="chapter" id="num_2" playOrder="2">
<navLabel>
<text>2. Has Disney Lost Its Mind With Its Latest Annual Pass Hike?</text>
</navLabel>
<content src="index_split_003.html"/>
</navPoint>
<navPoint class="chapter" id="num_3" playOrder="3">
<navLabel>
<text>3. Reasons to Plan a Late-Summer Trip to Orlando</text>
</navLabel>
<content src="index_split_004.html"/>
</navPoint>
</navMap>

only three file link here. missing to file link index_split_001.html and index_split_000.html

Can you explain me how we add missing file link in toc.ncx file

Thanks
Ramesh