Sometimes AX doesn't work as expected even if changes has been made to a code. Here are some suggestions

Compile

Compile and recompile.

License

While coding in a class, make sure that you have a x++ license, otherwise every changes made to a class will not be used.

Close the debugger
Sometimes, when the debugger is active, AX will keep executing ‘old’ code. Close the debugger to make sure the latest code is executing.

Synchronize data dictionary

Open the specific tables and synchronize or if everything else fails, just synchronize the whole AOT.

Restart AX

Simple as that, close the AX client and start it again.

Reset usage data
Go to options screen (AX button > Extra > Options) and click the Usage Data button. Click reset to remove this data.

Check the application event log for clues
Open the event viewer on the AOS to see if the AOS service has logged something in it. Messages here can help you a great deal. You can also check the event log on the database server or your client pc.

Delete AUC file

The application Unicode object cache file, if there is one, is located at C:\Documents and Settings\[USERNAME]\Local Settings\Application Data for xp, or C:\Users\USERNAME\AppData\Local for vista. Delete this file while the AX client is closed.

Full compile

Restart AOS

Remove .aoi file