The problem is likely a scoping issue. If you execute the code

if ($ff1) {
    my @a_ff1 =  &GetRow("$ff1")
}
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@a_ff1 is scoped to the if loop. Can we see more of the code surrounding your assignment? Do you see the expected result if you run

if ($ff1) {
    my @a_ff1 =  &GetRow("$ff1");
    print join "\n", @a_ff1;
}
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in place of your existing assignment? See Variable scoping in perlintro.