How can I validate if a fileformat exists on a folder

[apeso]

Have tried to do something like this when I have at least a file with .dll extension:
 

Code:

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if("D:\Harvest\02_GVP_IVRIntelPiloto (Piloto)\PGVITPL.21.12.06.1746 F-118933 - Copy\*.dll")
    out "exists"
else
    out "don't exists"

But it outs "exists" despite I have moved all .dll files to somewhere else .