Instruct: Classify a given Amazon review into positive or negative sentiment.
Query: A complete failure.

I tested the Opteka RC-7 Wireless Remote on my Canon EOS Digital Rebel XT and on my XTi. I used the Opteka directions and those supplied by Canon for each camera. The Opteka activated the XT once but froze the camera for regular, shutter-driven operations. I had to purge all settings to restore operations. The Opteka did not work at all on the XTi. Don't buy this product.