If record in subform exists then...

[epardo87]

ProdName = DLookup("[Producto]", "[Products]", "[PN]=" & PCode)

If DCount("[Producto]", "[Child6]", "[Producto]='" & ProdName & "'") > 0 Then 'Product name value will not be available inside the quotes, it must be in the base code. Type it in lower case, if it snaps back to your capitalization, then the code can see it.
MsgBox "found"
Else
MsgBox "doesnt exist"
End If

Thanks for your suggestion, I tried it as far as I could, but I just couldn't make it work... since this topic has already consume a bunch of time, I decided to simply go for another solution to what I was trying to do, is not as nice as it would've been if I had made this work but does the job, thank you all for your time