The input of this XML file
<results batch="20071002164716">
<result>
<student>M2776058</student>
<assignment>mu120.module1.formative</assignment>
<score>100.0</score>
</result>
<result>
<student>R8084284</student>
<assignment>mu120.module1.formative</assignment>
<score>33.333333333333336</score>
</result>
<result>
<student>U2627414</student>
<assignment>mu120.module1.formative</assignment>
<score>83.33333333333333</score>
</result>
<result>
<student>U6623136</student>
<assignment>mu120.module1.formative</assignment>
<score>66.66666666666667</score>
</result>
<result>
<student>W366938X</student>
<assignment>mu120.module1.formative</assignment>
<score>50.0</score>
</result>
<result>
<student>W6121062</student>
<assignment>mu120.module1.formative</assignment>
<score>44.44444444444444</score>
</result>
</results>

fails with [[baduserid]]

But if I edit the student IDs by hand to the student numbers I get when I export and provide this file
<results batch="20071002164716">
<result>
<student>11</student>
<assignment>mu120.module1.formative</assignment>
<score>100.00</score>
</result>
<result>
<student>12</student>
<assignment>mu120.module1.formative</assignment>
<score>33.00</score>
</result>
<result>
<student>13</student>
<assignment>mu120.module1.formative</assignment>
<score>83.00</score>
</result>
<result>
<student>14</student>
<assignment>mu120.module1.formative</assignment>
<score>66.00</score>
</result>
<result>
<student>15</student>
<assignment>mu120.module1.formative</assignment>
<score>50.00</score>
</result>
<result>
<student>29</student>
<assignment>mu120.module1.formative</assignment>
<score>44.00</score>
</result>
</results>

then the Grade book reports 'Grade import success' ... but the success is short-lived as all the imported scores end up in the Grade book as 0.00.