[RO Spacecraft hitting Atmosphere very fast Whats wrong?]

Hello I played KSP 1.9.1 with Real Scale Boosters today.

I wanted to launch a satellite in an 53 degree inclination orbit.

The targeted Altitude was 300 Kilometers.

I tried to launch 5 times without sucess.

I flew on a Atlas V, after Meco and stage sep and SES 1 I fired the engine with full power.

My apogee was 300  Km but everytime I reached the apogee to fast (after 1,5 minutes after stage sep) after passing apogee my altitude increased very fast and at 100 Km my vehicle exploded.

Whats the problem?

I‘ve also tried mechjeb at the last try.

Thanks 

Fly save

[KK‘s launcher with RO and RSS]

Hello,

is there a way to play KK‘s launcher SpaceX mod with RO and RSS so that the rockets have the right configuration including size and fuel? 

And is it also possible to optimize Tundra‘s exploration with RSS and RO too?

A instruction with the right KSP version and the settings/codes of  mod would be really cool!

Thanks and greetings from germany!