can't open 060019 in command line after "install and uninstall 060043"

Dear David and grasshoppers,

The problem is that after I:
1. uninstall the 060019
2. install the 060043
3. uninstall the 060043
4. reinstall the 060019,

I couldn't open the 060019 version of grasshopper by typing "grasshopper" in the command line of rhino.

However, I can still run the 060019 version by drag the grasshopper.rhp file into rhino and then type "grasshopper" in the command line.

Did anybody encounter the same problem?

Hope you can help!

Thanks!