How to debug Sharepoint project other dll reference

hi,

i have a sharepoint visual webpart project to which i added a dll referece (weather.dll) for using the methods, and my intranet site has 2 languages, but the thing is the webpart is working only in english site so i tried to debug the Sharepoint project and i was not able to debug the methods which i am using from the weather.dll

i am getting the exception error ( object reference not set to an instance of the object )

so is there any way to debug the dll reference which i added to the project.

Thanks

sal