Ndef wet parameter issue

Hi. I added the following method as a shortcut:

+ Ndef {
    fx {
        /* FX Shorcut */
        arg number=1, wet=1, function = {|in| in};
        this[number] = \filterIn -> function;
        this.set(("wet" ++ number).asSymbol, wet);

I thought that it would be a nice and shorter way to do what the following expression does:

Ndef(\a).source = ...;
Ndef(\a)[1] = \filterIn -> {|in| ...};
Ndef(\a).set(\wet1, 0.5);

However, it looks like the \wet parameter is ignored. I can set it to a value but I’m unable to change it on-the-fly. I usually use the method like this, reevaluating these two lines while performing:

[ .. pattern array .. ].p(*method that turns an array into a Ndef+Pbindef*)
.fx(1, 0.5, {|in| LPF.ar(in, freq: \cutoff.kr(500)});

There is something I don’t quite understand causing this error. What am I doing wrong?