female drops eggs constantly in pond….HELP

I have a pond in the backyard with a waterfall and adjoining the pond I have built a log ramp into an area with a mixture of sand and dirt for egg laying. I have a pair of concentric dbt’s and the female is always dropping her eggs in the pond….rather than climbing out of the pond onto the log ramp to the sand pit. I an desperately trying to breed this pair and was wondering if others have had this problem. I have been retrieving eggs when I see them in the pond and have burried them in the pit to hopefully hatch. I was wondering if others are using incubators and what kind of setup was most effective. If you can help with advice, I would greatly appreciate it. RCFTX.