Playsms app not working properly

Hi

I’m using playsms with kannel to configure for a GSM model.
I have installed kannel and playsms successfully.
Playsms application is getting opened in browser but when i try to configure few settings under Manage gateway and SMSC tab, its giving me a plain page. i’m unable to do the settings. All other tabs and features in the application are working fine.
PFA for the screenshots.
Please help me in this regard.
Thanks in advance!!!1