A file name with spaces has to be enclosed in double quotes.

lcCmd = ["C:\program files\sample dir\sample.exe"]
RUN  &lcCmd

>a='C:\sample\sample.exe'
>RUN &a
>
>works fine
>
>but
>
>a='C:\program files\sample dir\sample.exe'
>RUN &a
>
>does not work, what is wrong
>
>best regards