readfits failing, anyone know what this error means?

Hi people,

I'm currently trying to read some .fits data in, and readfits is not working. It works for other fits data I have but I get this error message for the new data I need to use:

 if true
    % code
Warning: Unable to determine format of the card value.
Returning the value as a string. 
> In fitsinfo>convertNumericValue at 1212
  In fitsinfo>getValueAndComment at 1023
  In fitsinfo>parsecard at 342
  In fitsinfo>readCardImage at 331
  In fitsinfo>readExtensions at 831
  In fitsinfo at 236
  In fitsread at 100
  In attempt at 9
Warning: Unable to determine format of the card value.
Returning the value as a string. 
> In fitsinfo>convertNumericValue at 1212
  In fitsinfo>getValueAndComment at 1023
  In fitsinfo>parsecard at 342
  In fitsinfo>readCardImage at 331
  In fitsinfo>readExtensions at 831
  In fitsinfo at 236
  In fitsread at 100
  In attempt at 9
Warning: Unable to determine format of the card value.
Returning the value as a string. 
> In fitsinfo>convertNumericValue at 1212
  In fitsinfo>getValueAndComment at 1023
  In fitsinfo>parsecard at 342
  In fitsinfo>readCardImage at 331
  In fitsinfo>readExtensions at 831
  In fitsinfo at 236
  In fitsread at 100
  In attempt at 9
Warning: Unable to determine format of the card value.
Returning the value as a string. 
> In fitsinfo>convertNumericValue at 1212
  In fitsinfo>getValueAndComment at 1023
  In fitsinfo>parsecard at 342
  In fitsinfo>readCardImage at 331
  In fitsinfo>readExtensions at 831
  In fitsinfo at 236
  In fitsread at 100
  In attempt at 9
end

At the bottom where it says "In attempt at 9" that is simply the name of my code at the location of readfits. I don't know how it determines the format of the card value but other programs for viewing fits data such as ds9 work. I am stumped, and have been for a few hours. Any help would be much appreciated.

Thanks

[Geoff Hayes]

Rob - just to confirm, fitsread works for some FITS files that you have, but not for the "new" one. What happens when you run

 fitsdisp(filename)

where filename is the name of your FITS file? What do you see?

What could be different about this file when compared with the ones that work? Is it older or newer?