I was skeptical
Well don't be - it's not the first time this has come up, which is why your problem was solved in the first response... it shouldn't really take twelve more posts before you've been convinced to give it a whirl on the off chance it's right!
As I understand the command PositionEntity, it sets coordinates in absolute space. MoveEntity moves the entity.
The difference between them is that MoveEntity takes values that are relative to the entity's current position (either in local or global space) while PositionEntity takes values that are absolute (again, either in local or global space). It's two different ways of describing the target coodinates, not two different ways of describing how to get there.
If you want a collision-less way to place entities that have been involved in Blitz's collision system then try something like...
Function PlaceEntity(ent,x#,y#,z#,Global) HideEntity ent PositionEntity(ent,x,y,z,Global) ShowEntity ent End Function