I keep getting butchered, am I doing something wrong?

I have a level 20 NecroRanger, 7 level 20 heroes/henchmen in my party (both healers&fighters), Sunspear/Istani armor (60+15 armor each), I have my skills under control AND all attribute points spent wisely.
But still, when I go into areas with 20 to 28 level foes, my party and I get slaughtered without mercy. Is that something standard and should I just avoid the foes the best I can, or is there something I'm missing?
Spanks in advance!

Just post your build and your hero/henchmen setup. Then we can help.

If you run in 10 mobsquads at the same time you're likely to fail even with the best stuff.
You should also play wisely. Make sure you see what you are aggroing and that you're not standing in paths multiple groups are walking on. Retreating is also not something bad.

Check your heroes energy management, target monks first, and I would advise not to use superior runes (major at most) then equip heroes with survivor insignia.

yes we would need to see your builds so we can help one thing to check also would be make sure your heros are set on guard so they dont go aggro crazy and just run and attack everyone in sight

Take a screenie of your builds and we can have a look at it.

And it would help if you mentioned which zones you are having problems with...

Without more information from the poster, this really isn't a good blanket statement. All of my heroes use superior runes and none of them have any survival problems.

Yeah, mate, tell us:

1. what area you're going into
2. which henchies you're bringing with ya

You can be a great player, but if you forgot to bring a healer, you're gonna get killed.

If you're using melee, establish a Frontline. Approach a group, Stop just short and if your melee are set to Attack Mode..they, hopefully, will start the battle. Follow them in. Otherwise your whole group IS the Frontline. Also, sounds like a Energy problem..Not to mention skills..such as Anti-melee. And especially a Mesmer on your team.

your heroes are not mathematically at there best then... not only should your heroes have good builds... they need equipment that complements their builds.... IE Minion master insignias and bloodstain insignia for minion master... instead of just slapping radiant or survivor on everything... personally i like to use one superior rune on the heroes primary build attribute, others don't it really depends on the build on class... IE sup death magic for minion master... your heroes will reflect how much effort u put into creating them.

GW is team based game, the more everyone skills work off each other the more successful you will become. IF you are taking all A.I. around with you grab a Ward ele to put down some wards, Ward Against Melee, ,Ward Against Elements, Ward Against Harm are very good armor boost.
Have a Necro/Mes take Enfeeble, Weaken Armor and Epidemic to spread conditions.
Since you have melee in your group put Barbs and/or Mark of Pain on the necro for extra damage boosts. If energy is an issue put Blood Ritual on the hero he will automatically put it on anyone with a caster weapon equipped.
Don't forget to bring condition and hex removal skills on both Healers/Prots.

There are many different ways to build a team in GW, just have to find the right combination for you.

You're right, I have no clue what his heroes are running, but most of the time I find superior unnecessary on anything except caster's and even then it's only Death Magic, Channeling, or Energy Storage (only for prot. ele). Heroes tend to spam certain skills and run out of energy. If he isn't targeting monks or have enough fire power to take them out the fights may take longer. I was mostly talking about Hard Mode since Normal Mode most of what I said isn't too game changing.

Pulling is very important in more dificult areas. If you pull you will avoid being swarmed by too many enemies and you'll make the mob disposition itself, making it more vulnerable to aoe damage.

I won't say it's a must, but minionmasters, a panic mesmer and a spiritspammer will make your life much easier.

I do dare suggest that you can take a look here http://www.gwpvx.com/PvX_wiki, maybe you'll get some inspiration and figure out what's wrong with your teamsetup.

As others have said, I can't really give any less general tips as you've given too little info.

I agree that good pulling is very important...

But i always make sure that none of my heroes are set to "fight". My fighters get "guard" and the healer(s) gets "avoid". I think they do less stupid things this way (listen better)...

Flatbow beats Longbow for pulling it has the longer range, don't let the name fool you.

Flatbow and Longbow both have the same range. However the flight time of the Flatbows projectile is 50% longer, giving you more time to run back to your party.

http://wiki.guildwars.com/wiki/Bows

Make sure all heros are setup correctly for the builds you want.
Make sure you pull each mob - like other says use a bow to pull.
Now there are many ways of pulling and probably the safest is to pin your team just behind you - you go forward and bow pull and retreat to team.This ensures the team attacks the first foe and wears him down ready for the mob.I say pin back as ive seen many times heros that ai says rush forward to the mob and they cause the pulling probs .
Caution is always best used and never rush a mob as you cant always see another mob on similar patrol path and 1 mob may turn into 2 and many deaths.

Also the Flatbow has a higher projectile arc, meaning you can shoot over higher obstacles than with the longbow.

On the other hand, the flatbow is more likely to miss, meaning you may need to try pulling more than once (not a biggie).