Peptide not flexible in docking

I built a peptide using pyPept but unfortunately, when I dock the peptides with my protein HADDOCK is unable to change the conformation of the peptide (the peptide in the docking results are too similar to the starting structure).
I changed the following parameters in the run.cns file, are there any other parameters I should change?
And just to ensure, did I define the fully flexible peptide correctly? it is segid B and set to malecule 2 (or should I have changed nfle_2 also?
I am using restraints of active and passive residues and local version.

Thank you!

{* Fully flexible segments for molecule 2 }
Note that current max is 5 (edit the run.cns to add more segments }
{===>} nfle_2=0;
Residues of molecule 2 at interface *}
{+ table: rows=5 “segment 1” “segment 2” “segment 3” “segment 4” “segment 5” cols=2 “Start residue” “End residue” +}
{===>} start_fle_2_1=“5”;
{===>} end_fle_2_1=“16”;

{* number of MD steps for rigid body high temperature TAD }
{===>} initiosteps=2000;
number of MD steps during first rigid body cooling stage }
{===>} cool1_steps=2000;
number of MD steps during second cooling stage with flexible side-chains at interface }
{===>} cool2_steps=4000;
number of MD steps during third cooling stage with fully flexible interface *}
{===>} cool3_steps=4000;

Your should set nfle_2=1 is this case if you want your peptide to be fully flexible.

Thank you!
Does that mean then that it didn’t change the peptide to flexible from amino acids 5-16? since I didn’t do
{===>} nfle_2=1;

Yes indeed

But the docking results came out differently when I used flexible (in the wrong way) or didn’t use them. Is that because Haddock has some randomness involved? or it does still make some difference.

There is indeed some chaotic nature to this type of computations, especially if run on different hardware. But I would not expect major differences unless some other parameter settings are changed.

And if you kept default settings for the semi-flexible segments your peptide would have some flexibility anyway