Field In Table Not Allowing Certain Characters

Hi Folks,

I have a table called tblSchemeCodes with the following field names:

Field Name Data Type Field Size Required Indexed

strCompany Text 1 Yes No
strSchemeCode Text 3 Yes Yes(No Duplicates)
strSchemeName Text 100 Yes No
strOrigNo Text 9 Yes No
strCategory Text 9 Yes No
dtmDateAdded Date/Time No No

Here is an example of some of the scheme codes I have:

HG
HGA
HGB
HGD
HGF
HGG
HGJ
HGP etc etc

however when I try to add HGE, it won't allow it, even though it doesn't exist within the table, it keeps changing it from HGE to HE, and HE already exists, so a can't add messgage pops up, which is should, because duplicates are not permiited.

I've tried turning off all of the required aspects and changed the "Yes (no Duplicates)" to "No", and the problem persists!!

Has anyone any idea why access would behave in this way and how I might resolve it.

Any assistance would be appreciated

John