Why does chain keep jumping off the rear sprocket on my Funduro????????

[BENJI]

I need help. I have had my Funduro (1999) for a year now. The chain has come off the sprocket at least 5 times already. This last episode is not long after a new chain and sprockets were fitted. What reasons could there be for this besides the obvious loose chain?
Thanks. ??? :xxbah:

 

[Eisbein]

 

[throttle jockey]

 

[spankme]

 

[Wildcoast]

 

[mox]

 

[lowrider]

 

[lecap]

 

[BENJI]