I'm using VTScada to run an application linking this software to MATLAB through Excel.
When writing from Matlab to Excel,and Excel to MATLAB, everything works fine.

When using VTScada as DDE Server,and writing data to my Excel, by using the following formula:

=VTS|'NewApplication'!'L1\Value'

I get a message telling me that I have to open VTScada,even if the problem is already running. I check on 'yes',then getting an error message telling me : "impossible opening VTS.exe. One of its components is damaged or missing"

I tried running both problems as an admistrator,but it still doesn't work. What should I do?

Starting with VTScada 12.0, DDE is disabled by default for security purposes.

To enable it the VTScada process must be started using either the /D or /d option. See the help topic Use VTScada as a DDE Server for more info.

Also see this info from MS about DDE disabling in Office products.