Cant use SIRIL output files in other programs

Eg, I have made a master dark in Siril.

The output file has an extension .fit

But it wont open in any other program. Ive tried in both 16bit and 32 bit.

in ASTAP, its a black screen saying :Custom Extensions"
In Sharpcap, its just black - no histo at all.

Any suggestions?

Thanks

I think you did used compression.

That sorted it. Plus keeping it at 16bit for Sharpcap.

Thanks