Confirm that the target file is ok (test by MOVEing the file from a command prompt) and if that works try one of the following:
 Code:
MOVE "C:\SuppAsstTest\kixforms.dll" "C:\Windows\System32\" /H /R

or
 Code:
MOVE "C:\SuppAsstTest\kixforms.dll" "C:\Windows\System32\kixforms.dll" /H /R


There is no "Elevated" parameter for the vanilla KiXtart SHELL command, and this is what is causing the "file cannot be found" error.