TryStringToInt, no overloaded procedure

begin
  PreviousRow:=Row;
  PreviousCol:=Col;
  Row:=StgCurrentCases.row;
  Col:=StgCurrentcases.Col;
     If Col = 5 or 6 or 7 then
       If trystrtodate(stgcurrentcases.cells[Col,Row]); then

Using Delphi7, won't compile because there isn't an "overloaded version of trystrtodate".

what do?

Code truncated because does it really matter what it says after that?