Elderflower liqueur: flowers turning an awful brown! Help!

I made about 8 jars of Elderflower Liqueuer using 42 proof vodka.
I filled the jars with the flowers, covered in Vodka with a lemon slice on top. All was good for the 4 weeks. A light golden color.
Then I strained the liqueur in coffee filters, two times each. I then added a sugar syrup as the recipe called for. I then sealed it again, however 3 weeks later they all turned murky and dark brown, except for one.
What happened to the seven murky, dark brown jars?
Should I strain them again or throw them out?
Help!!!!

Thanks so much, mainecook61! I'm so happy to hear your success story. I still have the liqueur tucked away, and haven't strained it yet. Now I will.

I made it. I submerged elderflowers in vodka in a quart jar. Yep, they turned brown, slowly, from the top down. It wasn't bugs or wilted flowers---that's just what happens. No food safety issue here--those flowers were pickled in alcohol! After more than a month (I kind of forgot about it), I strained the liquor, which had turned a light caramel color, and added 1/3 cup sugar. It's lovely. It tastes like brandy with flowers in it.

Here is a recipe for Elderflower Cordial (as it is known in the UK). It does not have alcohol, but produces a wonderful base for drinks. I have made this many times. Sometimes I have not used citric acid (not always easy to find), but have used lemon juice. The flowers did turn brown in that case, but did not really affect the result. Be sure to pick your flowers in the early morning. That does make a difference.
ELDER FLOWER SYRUP
4-1/2 ounces elderflowers
1 cup sugar
under 2 pints water
1/4 oz. citric acid

Put flowers in a large pot. Boil water, add sugar and citric acid. Pour over flowers and let stand for 24 hours. Strain through coffee filters. This may take a while. Don't worry about bugs. They will be taken care of (!) by the boiling water, and then they will be filtered out as you strain.

I usually triple (at least) this recipe.

definitely not with the current batch, those flowers sound wilted and the aroma would have been shot along with it as well.. Good luck with the liqueur!

Good call for future batches, Panfusine. I'm still not sure, though, whether or not the current batch is salvageable.

or.. if they're in a bottle, tie them in a loose muslin cloth with a couple of those Pie weights or glass marbles & then pop it into the bottle. Wouldn't recommend using metal, dried beans or peas though.. that may wreck the flavor

you may want to 'imprison' the flowers in a tea infuser & then drop them into the vodka so that they sink...

I have not made Elderflower liqueur myself, just thought that might be one reason. They are light so they will float, but I think you might try to flip the jar on its lid if you decide to give it another try. That way the air will travel through the liquid and might give it a better seal to possible oxidation if that is the problem. The other thing I can think of is the if the flowers themselves had some "bugs"; not quite sure what Elders are susceptible to. I remembered reading this post recently.
http://honest-food.net/veggie-recipes/sweets-and-syrups/elderflower-liqueur/

@Droplet: Yes they were! I totally meant to mention that. Is there something that you're supposed to do to help submerge them in the beginning? It seems that they like to float. Thanks!

Were the ones that turned brown submerged in the alcohol or "peeking" above the surface?