A lot of information is missing to be able to give any advice:
What client OS are you running?
What version of the View Client are you running? (If its really the open source version then you should know that its not updated anymore and have been replaced by a closed source version.)
What are you trying to connect to?
What version of View Connection server are you using?
What is the version of the virtual desktop you are trying to connect to?
What is the version of the View Agent on that desktop?
// Linjo