what is the size of your PCR product?

If your primers are not 100% efficient, then your dilution calculations based on those results won't be accurate.  It is possible to have too much cDNA template.

Also, double-check your math and make sure your micropipettes are accurate and precise.  It's easy to make a simple mistake in making serial dilutions.

i would suggest just try to do linear amplification in droplet with forward and reverse primers separate..  may as clark was mentioning its because less optimal design of your primers

my PCR product is 166bp, I really appreciate all your answers, I will try these nice suggestions.