There are some things that will help us give you a better answer. Most of all, what module you are using. Most likely, this would be something like Net::Telnet, and second, what the raw input data from the remote session looks like. For Net::Telnet, you would be able to obtain this input by using its debugging facilities.

Most likely, you are fighting the prompt of your remote terminal respectively how to match the remote prompt of your terminal with the regular expression in the configuration of the module. But without seeing the remote prompt and the regular expression you're using, it's hard to diagnose where it goes wrong.