3rd Guard Ulan Regiment Uniform- Istanbul Military Museum, Turkey

Chris’ Curious Museum Finds
3rd Guard Ulan Regiment Uniform- Istanbul Military Museum, Turkey
This is a display of a Tschapka, Ulanka, Hosen and portrait of 3rd Guard Ulan Regiment. The caption says it was worn by Ekrem Akömer during his service as Aide de Camp to Kaiser Wilhelm II. My question then is, does anyone know what years Akömer served in this task?
I like the display mistake by the way. Using the Tschapka oval cockade as a throat badge on the Ulanka is an interesting idea and I think looks quite good. What do you think?
Istanbul Military Museum (Askerî Müze), Halaskargazi, Vali Konağı Cd. No:2, 34367 Şişli/İstanbul, Türkiye