Could you give an example of which route you are trying to add? What I read between the lines is that you are something like 10.10.10.14 /26 as a route, which will give you this type of error. In routing you should always use the subnet address, not the host address if you want reach the hosts in that network via the added route.
Subnets use bit boundaries and there are for each subnet mask a list of possible numbers. ie for a /26 network only 0, 64, 128 and 192 are valid numbers as the network address so 10.1.10.64/26 is valid but 10.1.10.129/26 is not.
I hope this clarifies things a bit?
Regards, Maarten