I have never had a problem. Make sure you have Latitude set as N, and Longitude set as W before pointing to the corner and double clicking. If Longitude is left at E on any of the corners, you will have a problem.
trapper

See Topic "Topo State Series" on page 2 of this Thread, "Maps".
by trapper. I have the 710, but it should work on the 610 also.
Here is a copy:
You can view the exported maps from NG State series on eXplorist 710:
(1) Create a Topoquad RMP file from National Geographic TOPO! State series exported map.jpg
NOTE: the RMP files will fit very well when using the Custom grid and Snap to Grid features.
(2) Convert Topoquad.rmp for use on Magellan eXplorist 710
Software needed;
(1) National Geographic TOPO! State Series
(2) Magellan Triton Raster Map maker by Mikhail Sharonov from http://www.msh-tools.com
download TritonRMP.zip (Thank you, Mikhail)
(3) RMP Fix for RMPcreator & Magic Maps by Sockeye. Application "RMP Tools"
download from http://maps4me.net/tools/RMP_Tools.zip (Thank you, Sockeye)
(4) Your photo editor or download Paint.NET from http://getpaint.net/index.html
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Open TOPO!
Start with new map>GO.
Choose a state, zoom to your area, at least level 3 of 5
View Menu> Grid to get popup "TOPO! Grid Wizard"
*NOTE: View>Grid is a toggle, turns grid on/off
1. Choose a grid type and interval.
Select Lat / lon grid lines spaced every 450 seconds (this will space grid lines 7.5 minutes apart)
NOTE:This is the Standard size for USGS 7.5 minute series quadrangle maps.
2. Specify the map level that should display this grid.
Select All map levels
3. Pick a color for the grid lines
(I picked Blue Solid) pick your preference.
Finish
View Menu>Preferences
Units> Coordinates
Select Degrees and Decimal Minutes and NAD83/WG84
Printing / Exporting
Marginalia> clear all selections
Notes and Photos> clear all selections
Magnification>Select Print maps using the suggested magnification
Additional Settings>Select Snap Selection To Grid
Page Orientation Select Portrait
Select OK
File Menu> Export Map to Disk
a red rectangle with an X through it will appear
adjust this rectangle to cover a 7.5 X 7.5 grid then move the rectangle to the area you want to export
Notate coordinates of each corner
*NOTE: because of Snap to Grid Selection, minutes will be one of : 00.0, 07.5, 15.0, 22.5, 30.0, 37.5, 45.0, 52.5
* do not notate anything other than one of these.
you can revue "Options" at this time
Zoom to maximum
Save Map as type JPEG best> name your map> Save
*NOTE: Save several different adjacent maps then process them separately after exiting TOPO.
Exit TOPO!

Open Paint NET
Menu File> Open (open your saved map file)
View Menu> Actual Size
Scroll to top of map
Tools> Rectangle Select
Select from top of map to margin at bottom of map.
*NOTE: margin is 88 pixels high.
Menu Image> Crop to Selection
Menu Save
Exit Paint NET
*NOTE: Your map should not have any margins now.

Open RMP maker
Reference Format
select 00 Deg, 00,0000 Min
File Menu> Import Image (s)
select your image
Scroll to NW corner
Tab 1
enter coordinates
point to corner> double click left mouse button
Tab 2
Scroll to SW corner
enter coordinates
point to corner> double click left mouse button
Tab 3
Scroll to SE corner
enter coordinates
point to corner> double click left mouse button
Tab 4
Scroll to NE corner
enter coordinates
point to corner> double click left mouse button
Select Calibrate
Select Create RMP
enter File Name
Save
Exit RMP maker

Open RMP Tools
Provider
Enter your preference
*NOTE: I entered TOPO
Map Group
Enter your preference
*NOTE: I use USGS 7.5 Minute Quadrangle Names.
Select Fix RMP maps
Fix the rmp files you have created for this Provider and Group
Exit RMP Tools

DONE!
I usually look at the new rmp files in Vantage Point first.
Open Vantage Point
MAPS select + (Add Maps)
select the rmp files you have created.
You can view them by adjusting zoom.
*NOTE: I have not had any failures yet.
I delete them before Exiting Vantage Point.
Exit VP

If all was well:
Connect your eXplorist 710 to your computer.
Copy the rmp files to the MAP folder on your eXplorist 710 SD card.
Disconnect your eXplorist 710 from the computer.
When the explorist has booted up.
View Maps
Select Image Maps
Scroll to TOPO (if that was the provider you entered)
Your Map Group will be displayed under the provider.

Power OFF your eXplorer.

At this point you can use VP to manage the maps on your eXplorist 710.

I was unaware that the 510 - 610 and 710 units could handle National Geographic raster maps. Is this true?

"S"

As a recent discovery...you could just wait for a bit for the new Vantagepoint software to come out (pretty soon) as some of us have gotten ahold of it and it has NatGeo Topo integrated into it!!!! YIPEE!!