is ID field Number or Text Data type
if number use this codes
sSQL = "update tblLABBOOK Set CONTMAXNUM='" & [Text74] & "',CONTRVALNUM='" & [Text76] & "' Where [ID] = " & [txtID]
db.Execute sSQL
if Text use this codes
sSQL = "update tblLABBOOK Set CONTMAXNUM='" & [Text74] & "',CONTRVALNUM='" & [Text76] & "' Where [ID] = '" & [txtID] & "'"
db.Execute sSQL