я бы сказал "этого недостаточно" по-русски и amount по-английски

Не знаю разницы, но можно сказать to raise a sum, а можно и to raise an amount
http://www.azquotes.com/quote/988565

думаю, в современной жизни "sum" имеет гораздо больший арифметический оттенок.

Вот современный словарь: http://slovar-vocab.com/english-russian/general-dictionary/sum-3604441.html

http://www.nairaland.com/324455/how-raise-sum-50000-two

Elena, I agree with Grumbler about AMOUNT sounding better. "I'm working three jobs and THAT'S still NOT ENOUGH TO RAISE (-or better- GET TOGETHER, SAVE) the NECESSARY AMOUNT." I'm afraid that INSUFFICIENT FOR RAISING is grammatically correct, but unidiomatic as hell. https://books.google.com/ngrams/graph?content=insufficient+for+raising%2C+not+enough+to+raise&year_start=1800&year_end=2000&corpus=15&smoothing=3&share=&direct_url=t1%3B%2Cinsufficient%20for%20raising%3B%2Cc0%3B.t1%3B%2Cnot%20enough%20to%20raise%3B%2Cc0

Ok! What's the difference berween "sum" and "amount"? Uly, you missed "to" before "raise" ;)

Thanks for the correction, Elena.

There's not a big difference between the two words, except that SUM tends to be use more in financial or mathematical contexts. This post is just a general comment from one person to another, so SUM would sound a bit "technical" here (for lack of a better word).

Thank you.