Two softboxes with same flash power - Getting under exposed image

Hi,

Recently I tried cake smash photography of my daughter at my home. It was at late evening, hence had to use flashes. Gears used:

1. Nikon D3200 18 - 105 mm lens
2. Two Yongnuo YN560 IV flashes operated with remote trigger
3. Two soft boxes of 80 cm sq.
4. One backdrop

Flash power settings:
Both of equal power

Lighting setup:
Subject (my daughter), soft boxes and camera - All almost at floor level.
Both softboxes aiming at her face.
Representative image attached.

Outputs (After post processing):
Udhaya Kumar K - எங்கள் உலகிற்கு இனி #அகவை_ஒன்று :) Our... | Facebook

Problem:

I find the results more of underexposed and uncontrolled hard shadows. Most of the tutorials suggest me to go for one soft box with high power (Key light) and other with few stops lower power (fill light). Or to use a reflector? My question is why shouldn't I use two equal powered lights? What is the mechanism that causes this setup a failure?

Or, is my problem different than the power of lights?

Pl. provide feed back.

Edit - Picture updated with distances between subject and backdrop & subject and lights

 

Underexposure isn't a result of using two lights, using softboxes, using backdrops etc.

It's a result of not having enough light to produce a 'correct' exposure. Without knowing more (as mentioned, distances from lights to subjects), the light output of the lights, what the reflective properties of the softboxes are, and the camera settings, we're just guessing.

The shadows indicate the lights are far too high.

 

Thanks a lot @tirediron. I will do an identical setup but with softboxes closer and backdrop farther with the subject. But won't keeping the flashes farther with backdrops result in losing the colour of the background?

 

If the distance from the lights to the backdrop doesn't change, there should be no change on how it is rendered.

 

Thanks @480sparky

 

If I have to achieve a shot as here, what changes in setup would you suggest with the same gears?

http://www.blueberrybeignetphotography.com/wp-content/uploads/2013/08/474C9263-E-BBP.jpg

Thanks.

 

You can see the reflection of an umbrella in the purple balloons. Look closer, and you'll see it right at the corner of the table the baby is sitting on. This means it at the same level as the baby, just slightly to the left of the camera/operator.

The lighting in your original image just doesn't match the layout you've provided. The shadows indicate a light above and behind the subject.

You state your softboxes are 80 sq. cm. That's about the size of my hand. That's really not much of a modifier. The umbrellas reflected in the balloons is probably at least 36" diameter.

 

Thanks a lot! Let me try with the hints you have provided.

 

Thanks, @tirediron... In fact, I was worried that I bought something that I shouldn't have...