Dating existing trees with ages not matching the original ones

[Alexandra Gavryushkina]

Hi developers, 

Could you please help us with dating trees. We have a tree in a newick format, sequence alignment and the tip dates in a separate file. The tip dates format is as follows:

t890 5.0891585346
t493 4.6075151570
t454 3.6151298476
t752 3.4866719216
t512 0.9596362417
t659 1.6650818011
t769 2.5150377895

Then we use the following command to date the existing tree: 

iqtree2 -s pruned_tree_2_sequences.fasta --date pruned_tip_dates_2.txt -te pruned_tree_2_sequences.pf.nwk -m Dayhoff -pre dated

However in the output tree the ages of the tips do not match the given ones. Even if one rescales the dates assuming the program has scaled the whole tree,  they are still considerably different. 

Thank you, 

Sasha.