How to solve the following error in MSD AX..?

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Dynamics-AX

When I am trying to bind data set to my data methods then it fires following error message:

Data method 'GetEmplDetails' invocation failed. Fix the data method so that it returns a valid System.DataTable before binding to it.  Original error message:  Error executing code: IQ_ExitEmployeeFinal_1 (object), method GetJoinExitDetails called with invalid parameters.    (C)\Classes\IQ_ExitEmployeeFinal_1\GetJoinExitDetails

Where GetEmplDetails is the method in the class IQ_ExitEmployeeFinal_1

please help me as I am very new in MSD AX.

What I have tried:

I have tried at my level but as I am new to AX hence not getting proper idea,
plz help me.