Indicator Installation

I downloaded the platform to my computer (Vista) and installed a custom indicator to my experts folder in drive C, I could access the indicator on my charts and all was well. But later I downloaded another platform, thinking I could keep 2 mt4 platforms on my computer. The 1st platform was apparently deleted because of this, and I had to set up my charts on the new platfrom all over again. The only real problem now is that I can't access the custom indicator I installed when I 1st downloaded the platform. The file for this indicator is still in my harddrive in the experts folder, but the indicator itself doesn't show up when I go to the custom indicator menu on the platform. I've tried re-installing the platform and reinstalling the indicator to my computer, and I'm sitll unable to get the indicator to show up on my platform. Any guidance in resolving this problem would be greatly appreciated.