same thing happen to me. reason is simple you didn't "check" the circle for custom amount.

i did..i tick the circle and write 40...but nvm..i check my late mail came it reduce to 10 only..that y i need admin to check..whether something faulty there or not..and my creadit card provider says it i have use RM31(My Currency) with mean USD10..

since its paypal there is a receipt message sedy in the community messaging system and link him an image of the receipt to get it corrected so you can get your correct amount

All working fine this side, just checked it, so yeh must have not selected custom