Why Santorum Had Trouble Finding Delegates for Ohio's Congressional Districts

This was because the Ohio Congressional District map was highly contentious.  It was a massive Republican Gerrymander (ensuring a 12 to 4 advantage in a swing state).  Because of the threat of legal challenges and political roadblocks, the map was constantly in flux with the borders between congressional districts constantly changing.  The map was only finalized recently and by then, I reckon, Rick Santorum couldn't find the right people in the right location to fill out full delegate slates for the congressional districts that were in flux.