Not getting oven spring

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I was baked bread with pate fermentee, taste was good, but I'm just not happy with oven spring. Poor looking bread. I do not know where the problem is. Please help to find the problem.
Made a preferment, that stood overnight, about 12h, in room temp.
Flour 100%
water 60%
Salt 1.8%
Yeast 0,5%

Final dought
Flour 80%
Wwheat 10%
Wrye 10%
water 78%
Salt 2%
Yeast 0,7%
Preferment

Mixed everything, fold after 30min and let it rise about 50-60 min. Divided, shaped it into a ball and let it relax about 15 min. Shaped and placed in to bannetons. Final fermentation was about hour. Oven with baking stone and pan for steam, was preheated at 250 celsius  temp. Scored lengthwise, load bread and pour boiling water into the pan and sprayedoven walls  with hand spritzer. Lowered temp till 240 temp. After 15 min removed pan and baked 15 min.

I would be grateful for your advice.

You've given percentages that are unfamiliar. Flour = 100% which should include the whole wheat and whole rye. Instead what I think you've done is given the bread flour as 100% and the other two as a percentage of that. Bit confusing because if your water is 78% of the bread flour only, which would be a normal hydration for the final dough, then what is the actual hydration if you haven't included the other flours? I would think way too low. 

Another thing which looks wrong is there's not enough gluten formation.  

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Sorry, my bad. I'll correct the recipe, now it's ok. Need more folds? How many-1 or 2? My flouri s about 11,5% protein.

You are using an AP flour. While many do bake breads with AP flour it will affect the crumb and leavening. But it's not too low and you should be able to get a nice loaf out of it. I think it's down to gluten development. 

When forming the final dough give it a knead for 8-10 minutes. I'd say add in a few extra folds but you are making a quick bread and don't have much time to play with to incorporate folds with rests. If you don't wish to knead as you want a certain effect with the final crumb then you can do slap and folds at the beginning when making the final dough until the gluten is formed properly then go onto the bulk ferment. Or take a look at Trevor's videos on www.breadwerx.com and see how he mixes the dough and forms the gluten using the "rubaud method" which creates a nice and airy crumb. The folds he does through the bulk ferment (he does sourdoughs so has more time to play with) are just an added extra so you may incorporate 1 half way through. 

Consider the final proofing time to make sure you didn't under / over proof. Thats hard to know without knowing your dough temperature or yeast type. Assuming your kitten is around 25c and if dry yeast then this bread should spring fast as .7% is more like a fresh yeast percentage and you could go much lower with dry activated yeast so might be over proofed. 250c is a good temp but sometimes it can be 100f lower by the ti,ethe bread bakes thanks to heat escaping so it can't hurt to boost the temperature as well. Two spring killers are over,proofed dough and low heat :\

The other option is to put less yeast in preferment - do more like 0.2% over 12 hours and 1.2% in final dough. .5 is a lot over 12 hours. Hamelman suggests 0.2 over a 12 hour period and that's what I do - without problems. Breadwerx is a great resource if you're doing sourdough I've learnt so much from Trevor's videos. Good luck. Always keep a bread diary too helps eliminate mistakes and record successes as well as ideas and unforeseen fortune - I've found mine invaluable 

Thank for your suggestions and i'll try every thing that you suggest. I hope i improve my bread oven spring.