From a quick look the gauge is positioned way off the panel BMP.

[Window00]
file=IMG_3687.bmp

position=7
visible=1
ident=MAIN_PANEL

gauge00=Cessna!Altimeter,,505 <--- this is the & vertical position of the gauge in pixels. The BMP is 640 pixels wide.

Ok anyone want a Photo Realistic Piper Warror, Panel, Radio Stack, T&Ps Panel, And switch panel to have a go at?, Then if you want Ill send to one person, do the gaduges ect.. email it back to me then ill up load it sharing the credit, any intrest?

If you use the old CFGEDIT program or the replacement FSPANEL STUDIO it makes adding gauges so much easier it takes all of the guess work out of adding a gauge and you know what it will look like before you start up FS9 you can easily change a gauge size or place it any where you want it just click and drag you can put any gauge in your gauge file in any airplane in your fleet. What I like about it is you do not need to know the numbers as to where to put the gauge and in your case the numbers you used were wrong, just another reason to use one of the above programs.
CFGEDIT was a freeware program but I do not think it can be found anywhere anymore it was made for fs2002
FSPANEL STUDIO is the big brother of CFGEDIT and is made for FS2004 but is payware but I think the money is well worth it, as it makes adding gauges and windows a very simple tasks. 8)