How to put string on a single line, between xml tags with REGEX?

[me_suzy]

<AMG>
23Z 78R 899 DATA</AMG>

Output:

<AMG>23Z 78R 899 DATA</AMG>

My regex fail:

FIND: (<AMG>)(([\s\S]*?))(</AMG>)

REPLACE: \1$2\3

[me_suzy]

FIND: (<AMG>)[\r\n](.+)(</AMG>)

REPLACE BY: \1\2\3