How to fix Incorrect logical expression: Comparison/SELECT-OPTION can only be followed by "AND","OR" or ")". In an If Statement in SAP/ABAP?

Im writing a program where the idea is, if a Date that is given by the user is between 2 constant dates, then it should execute the following code. But I am getting an "Incorrect logical expression: Comparison/SELECT-OPTION can only be * followed by "AND","OR" or ")"." Thanks in Advance for the help.

IF sdate between date-djanstart and date-djanend. . . . ENDIF.