I "think" this is the listing for the Calvert City Cemetery that you identified:http://www.rootsweb.ancestry.com/~txrober2/cemetery/calvert_...
If so, read the notes at the bottom of the listing:
"The above list is based upon information provided by Cooper Wiese. It is also partially based upon information contained in Tombstone Inscriptions Of Robertson County, Texas by Inez Boswell Biggerstaff, 19 leaves, 28 cm, published between 1945 and 1968. It is also partially based upon information contained in the out-of- print book Cemeteries In Robertson County, Texas by Verna Corn Floyd and Vernelle Corn, copyright 1980, D. Armstrong Co., Inc., Houston, Texas. Some family information obtained from Historical Recollections Of Robertson County , by Richard Denny Parker, copyright 1955, Anson Jones Press, Salado, TX. Updates, additions, and corrections have been made as a result of extensive cemetery and family history research and the invaluable assistance from relatives of people buried in this cemetery. "
If you would also review the names, see the listing for "Wiese, Cooper." He was born in 1912 and died in Nov 2001. It is also based on information from 1945 to 1968. Since she died in 1991, it is probably unlikely she had died before the last transcription. Since there is also no stone, another reason she didn't appear in any transcription.
Again, contact her family for information.