I have a solution - leave it at 65% and don't worry about it. I personally prefer my cigars at that humidity. I don't usually add water until my humi hits 62%. I tend to find 70% too wet.
Or:
1. How did you prime your humi? I put a glass of distilled water in mine, wait a day or so for the humidity to get up to 70%, and then put in the cigars (after taking out the glass of water, of course).
2. Are you using only 50/50? Then add distilled water. Are you using only distilled water? Try some 50/50.
http://www.cigarsinternational.com/prodDisp.asp?item=M-HUM20-5&cat=10&page=all - either should do the trick
4. But if it doesn't - is your humidor any good? Does it have any gaps?
Bill