A very late reply, but it may help new developers. I had the same problem myself after entering data directly in Access. By examining working Gamebases, I found there are some minimum entries required for fields of the 'Games' table Unless you have alternative data, the following must be entered as a MINIMUM
[excluding the semi-colons

]
YE_Id = 1; FilenameIndex = 0 (zero); GE_Id =
1; PU_Id = 37;
MU_Id = 38; DI_Id = 8;
CR_Id = 7; TimesPlayed = 0; Ccode = 2; FA = -1; SA = 0; PR_Id = 1;
LA_Id = 1; Rating = 0; V_PalNTSC = 0; V_Length = 0 ; V_Trainers = 0;
V_PlayersFrom = 0; V_PlayersTo = 0; Prequal = 0; Sequel = 0;
Related = 0; Control = 0; Filesize = 0; Version = 1; V_LengthType = 5
You can also try the 'Scan and Fix Errors' facility in the GB Toolbox, which helps to remove null entries.