Keyboard up and down keys are not working

hello,
i just download desktop version and add some inventory and then try to create invoice when i search in drop box then try to press down key then nothing to happen! i can not select product via up and down key. kindly tell me solution for this
i use windows 7 32-bit.

Thank you

please search the forum before posting new questions.
this has been discussed many times.

But in this top not provide any solution till now no keyboard scrolling work kindly provide solution please

Instead of up and down keys - start typing the product name and the drop down list will change to suit, also you can use the mouse scroll button.

i am using latest version Manager 17.11.37 but keyboard scrolling not working!