i just finished my editing, and i want to export it by to bitmap but when it's done i can't open my image
detail of my project:
resolution : 16 X 6 Meters (sorry it's not in pixels)
dpi : 90
export to : png
any one knows what was wrong with my project ?
help me please.....
thanks.

16 m / 6 m = 16000 mm / 6000 mm = 629,92 inch / 236,22 inch -@ 90 dpi = 56693 px / 21260 px

Even photoshop would melt on that size.
However vectors don't need to be exported for printing, saving to pdf should be the way -oh wait, pdf also has a size limit, hmm...
Is there even a printer capable for printing a 6 m wide material?

What exactly do you working on?

here i working for a banner that may be can printing for 6 meters so that i take that size for my project
so, do you have any suggestion for DPI should i use?
i really need it thanks for your reply ............

I'd suggest to consult with the printer.
I found printed mesh only in 5 m width, there is a chance a 6 m wide print needs to be welded together from parts. Those printers probably use some cmyk profile, for best colour matching prepressing would be necessary after any export.
What dpi? The one I found was capable of 360 dpi, but

The Editor in Photoshop Elements limits the maximum dimensions of an image to 30,000 pixels by 30,000 pixels. You cannot open or create an image that is over the limit in the Editor

.
https://helpx.adobe.com/photoshop-elements/kb/maximum-image-size-limits-photoshop.html

200" is the maximum size for pdf-s, so saving your work as pdf won't help either (200"=5080 mm).