Check the
FAQs.
Q: If a unit declares a charge against an enemy unit that is
entirely on the upper level of a terrain feature such as a ruin,
Sector Mechanicus structure, etc., but it cannot physically end
its charge move within 1" of any models from that unit (either
because there is not enough room to place the charging unit, or
because the charging unit is unable to end its move on the upper
levels of that terrain feature because of the expanded terrain rules
for it – as with ruins, for example), does that charge fail?
A: Yes.