Problems with DME and low gravity

Did an attempt to brew an APA, with these ingredients

Boilsize: 6 Litre / 1.6 gallon
Batchsize: 9 Litre / 2.4 gallon

Ingredients Amount Item Type % or IBU
1,00 kg / 2.2 pounds Extra Light Dry Extract
0,20 kg / 0.45 poundsCaramel/Crystal Malt (steeping)
15,00 gm Chinook [13,00 %] (60 min) Hops 37,6 IBU
10,00 gm Amarillo Gold [8,50 %] (20 min) Hops 9,9 IBU
10,00 gm Amarillo Gold [8,50 %] (5 min) Hops 3,3 IBU
0,12 tsp Irish Moss (Boil 10,0 min) Misc
0,30 kg / 0.66 pounds Brown Sugar, Light (15,8 EBC) Sugar 20,00 %
1 Pkgs SafAle English Ale (DCL Yeast #S-04) Yeast-Ale

Estimated OG according to BeerSmith should be 1.054, but I ended up at 1.038?
Is there something like bad DME?
What else could have gone wrong?!

It's a pretty common issue for ANYONE topping off with water in the fermenter (and that includes partial mashes, extract or all grain revcipes) to have an error in reading the OG...In fact, it is actually nearly impossible to mix the wort and the top off water in a way to get an accurate OG reading...

Brewers get a low reading if they get more of the top off water than the wort, conversely they get a higher number if they grabbed more of the extract than the top off water in their sample.

When I am doing an extract with grain recipe I make sure to stir for a minimum of 5 minutes (whipping up a froth to aerate as well) before I draw a grav sample and pitch my yeast....It really is an effort to integrate the wort with the top off water...This is a fairly common new brewer issue we get on here...unless you under or over topped off or the final volume for the kit was 5 gallons and you topped off to 5.5, then the issue, sorry to say, is "operator error"

More than likely your OG is really what it's supposed to be. And it will mix itself fine during fermentation.

+1

OK, thanks for the info.

Do you have the option of doing a full boil?

I was going to suggest the same thing as Revvy, its probably just improper mixing. I did the same thing with one of my early beers but got the opposite result-the OG was supposed to be around 1.070 and what I measured came out somewhere near 1.115. A full boil would take care of the inconsistencies that come up when topping off with cold water, but if you don't have that ability (much like myself), just mix it really well before taking your reading. Good luck!