How do I maintain table borders when splitting cells in Wo..

I have an issue making a table with borders in Word. When printing the
document or making a pdf, the borders either become thinner or disappear in
cells that have been split. Becomes a real problem for the Power Point
presentation. Does not work well putting the table into Excel.
Example:
Table has five columns and six rows. Column D cell has been split
horizontally in all rows to have the ability to enter text top and bottom.
This causes Column A, B, C and E to loose the top part of the verticle border
in row 1. All other rows maintain the borders. All rows have been made to
equal height of 0.56; the split cell column is evenly split in height, 0.28.
Can you help? Thanks.