Some file what your ocx file needs not found client machine.

Check these files:
ole32.dll
olepro32.dll
oleaut32.dll
msvcrt.dll
msvcrt20.dll
msvcrt40.dll
mfc40.dll
mfc42.dll

if some these files missing client machine. That could be promlem answer.

View Dependencies your ocx file and here you found what files your ocx file needs to register and working.

-Dj4