If it seems you are doing the right plus or minus 600KHz on the repeater you want, then it certainly might not be that. Next to check would be that you are doing a CTCSS tone on your TX for the repeater. There's not much else you gotta do to use the repeater.
Not having used them, you would need to check the manual to make sure the offsets are correct. You can check the offset by using your icom and listening on the transmit freq. For example. If your listening on 147.24 the standard ham radio offset would put the input at 147.84. Your radio should be set to receive .24 and should transmit on .84. Normally the 147 range are plus 600 and the 146 are negative 600. The 145 can be both and all can have oddball offsets on rare occasion.
UPDATE: I have been using these radios for nearly a year in all conditions and have been very pleased with them, so much so that my Yaesu and Icom are getting used less and less.
The Puxing PX888 is my favorite, it's light, intuitive controls and receives FM radio frequencies. Because it's so light I throw it in my Camelback pack while mountain biking and listen to my favorite country station while riding and keep in touch with my wife through a local repeater if needed.
I initially purchased these radios to use on trips with multiple vehicles and loan them to friends, if they broke they were cheap and no big loss. Well my opinion is much different now and I loan out my Icom and Yaesu to friends and keep the Puxing for myself.
As you can tell I am very pleased. Great little radios.
Raising a thread from the dead. My Puxing radios are still going strong and are still my go to radio as I head out the door. Here is a link to the Puxing and a slew of other cheap radios but the site also has Yaesu and Icom.
I see that there was initially a bit of difficulty using them with repeaters. Was the solution simple?