java - Why does Java find one referenced class but not another in the same .jar?

Question

If I run:

java -jar myjar.jar

I get:

java.lang.NoClassDefFoundError: org/apache/commons/math3/stat/regression/OLSMultipleLinearRegression

However, if I run:

java -classpath '.:commons-math3-3.2.jar' -jar myjar.jar

I get:

java.lang.NoClassDefFoundError: org/apache/commons/math3/special/Erf

Any idea why this happened?

I just don't compute how the -classpath option can solve the "Class Not Found" error for one class but not for the other, when both classes do exist in the .jar added.

Or did I invoke the .jar incorrectly?