Update Links, DDE

I have a tricky problem that I need helping getting around. I use DDE to import data into Excel. When the there is no data streaming from the 3rd party softeare, Excel shows zeros in the cells, and when they are filled, it shows the respective data. When the data from the third party app is deleted, instead of showing that change on the spreadsheet, returning zeroes in all the cells, it simply stops changing (the data pauses at the last point before the data was deleted). However, if I close the spreadsheet and reopen it, I am prompted with the update links message box:

DDE_Sample2.jpg

When I click 'Update', it updates all links, and returns zeroes to all cells. What I need to do is find out what that 'Update' button is doing and how to set that to automatic, or write it into VBA.

Attaching the spreadsheets won't help because you need other software to retrieve the data, so I uploaded some pics to better illustrate.



With data feeding into Excel, the cells are filled with data. Cells that aren't receiving data are filled with zeroes:

DDE_Sample1.jpg


When the data stops feeding into Excel, the cells stop receiving data but they don't reset to zeroes. However, when I close and reopen the spreadsheet, and click 'Update' when prompted, the cells are reset back to zeroes:

DDE_Sample3.jpg


Any help is greatly appreciated.