[Typo3] anyone using jpgraph

[Vikram Mandal]

Hi *,

I need to use jpgraph in an extension. But I have this annoying error 
"General PHP error: Undefined Index:"

Seems like something to do with header. Anyone having a clue on how get 
  rid of it.

The jpgraph script otherwise runs fine.

There is a jpgraph extension in typo3 repository by Ingmar, but I get 
the same error with my Typo3 installation (3.8.0)

Thanks,
- Vikram