Date problems

Had previously ran into trouble with dates on this before. Sadly had to finally replace Microsoft's date picker due to compatibility issues. I have managed for most but not my completed tasks.

On the Currently on the go worksheet, when you click "Completed Tasks" the form appears.

I have two issues:

a: my macro that validates the to date is greater or equal to the from date seems to fail if the from date is a few years ago.
b: no completed tasks ever come through. The code that surrounds the new "date picker" is used elsewhere and works correctly. It just seems to be where I previously used the dateserial function in the comps sub routine to get over previous issues. I have tried a few combinations but just can't get it to work!

Any help is really welcome. Spreadsheet attached.

Thanks
Paul