Ocx Register Problem

Helllo;
I'm using 3d party ocx in my project. I made a setup program with my project and install this a different computer. After installation when i click to run program it's give "Component 3dParty.ocx not correctly Registered". Meanwhile i put necessary vb component in the setup package and register 3dparty.ocx manualy. In spite of this program doesn't work but when i install Vbasic 6.0 to on that computer, program begin to run.
What is this reason can be ?
Thanks