Not able to create CDT for few Tables

Question

Hi All, 
 I am using Oracle DB and in Appian want to create CDT for few tables. I am able to create CDT for few but for few I am not. Below is the statistics I noted.

Total no of columns in DB 
 Total no of rows in DB 
 CDT?

Table1 
 68 
 9977 
 Created

Table2 
 51 
 106881 
 Failed

Table3 
 45 
 14 
 Failed

Table4 
 42 
 26191 
 Created

Table5 
 41 
 14 
 Failed

Table6 
 36 
 60354 
 Failed

Table7 
 32 
 100878 
 Failed

Table8 
 32 
 328 
 Created

Table9 
 31 
 2559 
 Failed

Table10 
 29 
 39602 
 Created

Table11 
 29 
 21581 
 Created

Table12 
 29 
 268 
 created

Table13 
 28 
 13565 
 Failed

Table14 
 28 
 42 
 Failed

Table15 
 27 
 83742 
 Created

Table16 
 27 
 16792 
 Created

Table17 
 27 
 944 
 Failed

Table18 
 27 
 497 
 Failed

Table19 
 26 
 59 
 Failed

Table20 
 25 
 3480 
 Failed

Table21 
 23 
 5982 
 Created

Table22 
 22 
 195 
 Created

Table23 
 21 
 1236 
 Created

Table24 
 21 
 1126 
 Failed

Table25 
 21 
 339 
 Created

Table26 
 20 
 1688 
 Created

Table27 
 20 
 501 
 Created

Table28 
 19 
 88502 
 Failed

Table29 
 19 
 1286 
 Created

Table30 
 18 
 1073 
 Created

Table31 
 18 
 17 
 Created

Table32 
 18 
 0 
 Created

Table33 
 18 
 0 
 Created

Table34 
 17 
 12050 
 Created

Table35 
 17 
 604 
 Created

Table36 
 16 
 14157 
 Created

Table37 
 15 
 2913 
 Created

Table38 
 15 
 1352 
 Created

Table39 
 15 
 1236 
 created

I am failed to understand the pattern and behavior. Or I am missing anything here. 
 Sharing the error if the CDT creation is failed - The data source [name=jdbc/XXX] cannot be reached, does not exist, has been deleted, or you do not have sufficient privileges to access its data. 
 Please suggest any pointer.