sdk problem

[SUMIT0733]

when i implement this library in gradle.build and sync if, It sync and give me the error.
../../.gradle/caches/transforms-1/files-1.1/appcompat-v7-28.0.0.aar/ff1c465b622aca7882412f99ea6427fb/res/values-v28/values-v28.xml |  
error: resource android:attr/dialogCornerRadius not found. |  
app/build/intermediates/incremental/mergeDebugResources/merged.dir/values-v28/values-v28.xml |  
error: resource android:attr/dialogCornerRadius not found. |  
../../.gradle/caches/transforms-1/files-1.1/appcompat-v7-28.0.0.aar/ff1c465b622aca7882412f99ea6427fb/res/values/values.xml |  
error: resource android:attr/fontVariationSettings not found. |  
error: resource android:attr/ttcIndex not found. |    
failed linking references. |  

My compile sdk and Target sdk is 27 ,then why i got an error of sdk 28?

[fukemy]

same problem here