Leave Request dropdown is blank

I am using this url to accress My leave request app :

http://<server>......<port>/sap/bc/ui5_ui5/sap/ui5_hcm_lr_cr/index.html

When i click on request leave i get the following error as seen in the below screenshot:

On clicking OK four times and when i click on request leave the below screen appears,however the request leave dropdown is blank.What may be the reason for this?