Inserting a clip into timeline is replacing other clips

I know I have done this in the past, but I am having trouble now. I need to insert a clip into the timeline without splicing all of the tracks but just shifting everything on the affected track over.When I hold down control while inserting, the clip is overwriting what's in that spot already rather than moving it down.  I've tried shift, and it splices my other tracks. What am I doing wrong? Please help!