claims. "The probative value of other discriminatory acts depends . on the nature of the discrimination charged." Hunter v. Allis-Chalmers Corp., Engine Div., 797 F.2d 1417, 1424 (7th Cir. 1986), abrogated on other grounds by Patterson v. McLean Credit Union, 491 U.S. 164, 109 S. Ct. 2363, 105 L. Ed. 2d