Compatibility problem with memory

[arkanine]

I have this memory originally (crucial sport ddr4 2400 pc19200 Bls8g4d24dfs8)2x8,I bought Crucial 8 GB UDIMM 2400 MHz PC4-19200 DDR4 Memory (BLS2K8G4D240FSA) x2 they will run seperatly but not together??? what am i missing here?

 

[Calvin7]

The old memory has never been tested with the new memory, so there are no guarantees they will work together.

If your using two kits of the BLS2K8G4D240FSA, memory manufacturers don't guarantee combining multiple kits will work together.

Adding extra memory causes additional stress on the memory controller which can cause the memory to be unable to operate at its rated specifications.

Workarounds to get multiple kits of memory to work include:
Lower memory frequency
Relax DRAM timings
Increase DRAM voltage
Lower CPU multiplier