[NTG-context] Help : Unknown references

[WN]

Hi,

I am getting unknown references when I use
\startformula
\startalign[n=3]
.... Some math ......
\stopalign
\stopformula
in conjunction with
\placeformula[eqn1]
\startformula
.... math ..
\stopformula
See \in[eqn1] .... <----------- unknown reference

It has something to do with the formulanumber not set, I know, but how 
do I fix
this in the above ??

Thanks for your help and time
WN