call failed to a function – what am I missing in my page?

I am using the fMoblog 1.3 plug-in at https://mblog247.com/

I want to have a VERY SIMPLE index page for cellphone browsers so I created a cell directory and placed both a html and a php index page in this folder. SO you can visit either
https://mblog247.com/cell/index.html is what I am hoping to get
https://mblog247.com/cell/index.php is of course the page I need to use with valid PHP code

EVEN if your solution contains some hardwired code – absolute urls etc and not php calls – can someone tell me what will the https://mblog247.com/cell/index.php page need to get rid of that error?

thanks
Harry