Print preview doesn't work properly in Excel 2010

Hello all,

First I made some contents and drew a border from Home > Font > all Borders on an Excel 2010 file. So it became like below image (capture1). After that I wanted to print it so went to File > Print to see its preview. But the problem is that the lines between tue and wed and also between mon and tue are not shown neither in preview nor when printing. The height of row 7 until 17 is 24 (that is 32 pixel) but heights of the rest of the rows are normal (20 pixel).

Any idea about why those lines aren't shown?

Isn't there any solution!!?

No there isn't any merging data.
Look, I copied that form and pasted it into sheet3 (it was in sheet1). And increased the height of rows 7 till 17 from 15 (default) to 25, because reading data from printed paper his way will be more simple and also the amount of data and its format are so much more than this small form (I minimized the form so that finding the solution is simpler). After these works I pressed Ctrl+Z. There isn't any problem with preview!!
So I thought that problem is about something hidden in the background of the range B7 till D17 (the form). Therefore, I returned to sheet1 and selected the entire sheet (from the corner) and clicked on Editing > Clear > clear all. Then I again copied the form from sheet3 (which the preview for it was well) and pasted it to sheet1 (which now is clean apparently!) in range B7 till D17 and then increased rows (7 till 17) to height 25. Then tested it, BUT again I faced that problem, Why please?